Calculus 2 (Math 31 sections 02 and 04)

Class times for Section 02: 10:00AM - 10:50AM, MWF; 10:30AM - 11:20AM, Th (BRH 209)
Class times for Section 04: 12:00PM - 12:50PM, MWThF (BRH 209)
Office Hours: M 11:00AM - 11:45AM and 1:00PM - 2:00PM, W 11:00AM - 11:45AM, Th 1:45PM - 3:00PM, or by appointment

The general course information can be found in the course information handout below. Student grades are maintained on SacCT.

Handouts


Course Info

[updated 08.25.16]

Course Log

Week 15
[12.09.16] - Friday

We did it! Good luck preparing for finals! My office hours next week have been posted in SacCT.

- Miss you already! -

Sections covered: Review
[12.08.16] - Thursday

Sections covered: 11.10 (continued)
Reading for next time: None. Work on the homework and start reviewing.
To discuss next time: Just come prepared for some group work review.
[12.07.16] - Wednesday

Sections covered: 11.9 (finished), 11.10 (started)
Reading for next time: 11.10. Focus on the following:
  1. Introduction through Example 1
  2. Example 3
  3. Table 1 on page 768
To discuss next time: the relationship between Taylor series and tangent lines.
  1. Find an equation of the tangent line at $x=0$ for $\displaystyle e^x$. Compare your answer to the Maclaurin series for $\displaystyle e^x$ (on page 768).

  2. Find an equation of the tangent line at $x=0$ for $\displaystyle\sin(x)$. Compare your answer to the Maclaurin series for $\displaystyle\sin(x)$ (on page 768).

  3. Find an equation of the tangent line at $x=2$ for $\displaystyle e^x$. Compare your answer to the Taylor series at $a=2$ for $\displaystyle e^x$ (see Example 3 on page 763).

  4. Try to generalize your findings. Suppose $f(x)$ has a Taylor series at $x=a$ given by \[f(x) = c_0 + c_1(x-a) + c_2(x-a)^2 + \cdots\] What is the relationship between this series and the tangent line for $f(x)$ at $x= a$?
[12.05.16] - Monday

Sections covered: 11.9 (started)
Reading for next time: 11.9. Focus on the following:
  1. Examples 5, 6, and 7
To discuss next time: Let's practice building new series from old, via substitution, by trying to find a power series representation for \[f(x) = \frac{2x}{3+x}\]
  1. Use a substitution in the geometric series \[\frac{1}{1-x} = \sum_{n=0}^\infty = 1+ x + x^2 + x^3 + \cdots , \quad\quad -1\lt x\lt 1\] to find a power series representation for $\displaystyle\frac{1}{1+\frac{x}{3}}$. Make sure to find the new interval of convergence.

  2. Now use your previous answer to find a power series representation for $\displaystyle\frac{1}{3+x}$. Hint: notice that $\displaystyle\frac{1}{3+x} = \frac{1}{3}\frac{1}{1+\frac{x}{3}}$

  3. Modify your answer from the previous part to find a power series representation for $\displaystyle f(x) = \frac{2x}{3+x}.$

  4. Make sure that you can write you answer in closed form as well as expanded form.
Week 14
[12.02.16] - Friday

Sections covered: 11.8 (continued)
Reading for next time: 11.9. Focus on the following:
  1. Theorem 2 on page 754 and Notes 1, 2, and 3 that follow it.
  2. Examples 4 and 5
To discuss next time: Let $\displaystyle f(x) = \sum_{n=0}^\infty (-1)^n \frac{x^{2n}}{(2n)!}$. Writing $f(x)$ out, we get \[f(x) = 1 - \frac{x^2}{2!} + \frac{x^4}{4!} - \frac{x^6}{6!} + \frac{x^8}{8!} - \frac{x^{10}}{10!} + \cdots\]
  1. Find expressions for $f'(x)$ and $f''(x)$ by working with the expanded form of $f(x)$.
  2. Show that $f''(x) = -f(x)$.
  3. Find $f(0)$ and $f'(0)$.
  4. Meditate, hazard a guess as to a simpler formula for $f(x)$.
  5. Go to Desmos and graph $\sum_{n=0}^{25} (-1)^n \frac{x^{2n}}{(2n)!}$ to try to confirm your conjecture.
[12.01.16] - Thursday

Sections covered: 11.6 (finished), 11.8 (started)
Reading for next time: 11.8. Focus on the following:
  1. Theorem 4 on page 749
  2. Examples 1,2,4,5
To discuss next time: Let $\displaystyle f(x) = \sum_{n=0}^\infty \frac{x^n}{n!}$. Writing $f(x)$ out, we get \[f(x) = 1 + x + \frac{x^2}{2} + \frac{x^3}{6} + \frac{x^4}{24} + \frac{x^5}{120} +\cdots\]
  1. What is $f(0)$?
  2. For what values of $x$ does $f$ converge? (In other words, what is the domain of $f$?)
  3. What do you think is a formula for $f'(x)$? (You do not need to justify your answer! Remember, $f(x)$ looks like a polynomial.)
  4. Based on what you found in the previous parts, hazard a guess as to a simpler formula for $f(x)$.
  5. Go to Desmos and graph $\sum_{n=0}^{100} \frac{x^n}{n!}$ to try to confirm your conjecture.
[11.30.16] - Wednesday

Sections covered: 11.6 (continued)
Reading for next time:
  1. 11.7: Read everything (including the examples)! The section is short and helpful.
  2. 11.8: Introduction
To discuss next time: Meditate on the fact that "a power series $\sum_{n=0}^\infty c_nx^n$ is a function of $x$."
  1. Let $\displaystyle f(x) = \sum_{n=0}^\infty x^n$. Writing $f(x)$ out, we get \[f(x) = 1 + x + x^2 + x^3 + x^4 + x^5 +\cdots\]
    • Is $f\left(0\right)$ defined? (That is, does $f(0)$ converge?) If so, what is it?
    • Is $f\left(1\right)$ defined? If so, what is it?
    • Is $f\left(\frac{1}{2}\right)$ defined? If so, what is it?
    • Explain why the domain of $f$ is $-1 < x < 1$.
    • Explain why $f(x)$ is given by the formula $f(x) = \frac{1}{1-x}$ whenever $-1 < x < 1$.
[11.28.16] - Monday

Back to it.

Sections covered: 11.5 (finished), 11.6 (started)
Reading for next time: 11.6. Focus on the following:
  1. Definition 1 on page 737
  2. Theorem 3 on page 738
  3. Examples 1,2,3
To discuss next time: Think about the following questions related to \[\sum_{n=1}^\infty \frac{\sin\left(3^n\right)}{2^n}\]
  1. Explain why you cannot use the Comparison Test or LCT to compare $\sum_{n=1}^\infty \frac{\sin\left(3^n\right)}{2^n}$ to anything.
  2. Explain why the Alternating Series Test does not apply to $\sum_{n=1}^\infty \frac{\sin\left(3^n\right)}{2^n}$.
  3. Show that you can use the Comparison Test to compare $\sum_{n=1}^\infty \left\lvert\frac{\sin\left(3^n\right)}{2^n}\right\rvert$ to a convergent geometric series.
  4. What, if anything, does Theorem 3 on page 738 allow you to conclude about $\sum_{n=1}^\infty \frac{\sin\left(3^n\right)}{2^n}$?
Week 13
[11.23.16] - Wednesday

Break time!!

Sections covered: Exam
Reading for next time: 11.5 + Relax
To discuss next time: None. Relax.
[11.21.16] - Monday

Good luck with your studying!!

Sections covered: 11.5 (started), Exam Review
Reading for next time: None. Study.
To discuss next time: None. Study.
Week 12
[11.18.16] - Friday

Sections covered: 11.4 (finished)
Reading for next time: Start studying for the exam, but don't forget to check out the questions below.
To discuss next time: Think about the following questions related to $\sum_{n=1}^\infty \frac{(-1)^{n+1}}{n}$.
  1. Explain why you cannot use the Comparison Test to compare $\sum_{n=1}^\infty \frac{(-1)^{n+1}}{n}$ to $\sum_{n=1}^\infty\frac{1}{n}$.
  2. Explain why you cannot use the LCT to compare $\sum_{n=1}^\infty \frac{(-1)^{n+1}}{n}$ to $\sum_{n=1}^\infty\frac{1}{n}$.
  3. What's your feeling about the convergence or divergence of $\sum_{n=1}^\infty \frac{(-1)^{n+1}}{n}$? Write this down, with your reasoning, before going to the next part.
  4. Look at the Desoms graph here: https://www.desmos.com/calculator/npezpry5vc. The orange dots represent the sequence of terms $\frac{(-1)^{n+1}}{n}$. The black dots represent the sequence of partial sums $s_n = \sum_{i=1}^n\frac{(-1)^{i+1}}{i}$. Did this change or confirm your feeling about convergence or divergence? If you want, you can compare the previous graph to the graph of the terms and partial sums of the harmonic series here: https://www.desmos.com/calculator/3vvosxcslp.
[11.17.16] - Thursday

Sections covered: 11.3 (finished), 11.4 (started)
Reading for next time: 11.4. Focus on the following:
  1. The "Limit Comparison Test" (LCT)
  2. Example 4
To discuss next time: (carry over from last time) the series $\sum_{n=1}^\infty \frac{1}{n!}$.
  1. Explain why $\frac{1}{n!} \le \frac{1}{n}$ for $n\ge 1$.
  2. Explain why you cannot use the Comparison Test to compare $\sum_{n=1}^\infty\frac{1}{n!}$ to $\sum_{n=1}^\infty\frac{1}{n}$.
  3. Explain why $\frac{1}{n!} \le \frac{1}{n(n-1)}$ for $n\ge 2$.
  4. Show that $\sum_{n=1}^\infty\frac{1}{n(n-1)}$, which is equal to $\sum_{n=1}^\infty\frac{1}{n^2-n}$, converges by comparing it to $\sum_{n=1}^\infty\frac{1}{n^2}$ with the LCT.
  5. What can you conclude about $\sum_{n=1}^\infty \frac{1}{n!}$? And why
[11.16.16] - Wednesday

Sections covered: 11.3 (started)
Reading for next time: 11.4. Focus on the following:
  1. The blue boxes, i.e. the "(Direct) Comparison Test" (DCT) and the "Limit Comparison Test" (LCT)
  2. Note 1 and Example 2
  3. Note 2 and Example 3
To discuss next time: the series $\sum_{n=1}^\infty \frac{1}{n!}$.
  1. Explain why $\frac{1}{n!} \le \frac{1}{n}$ for $n\ge 1$.
  2. Explain why you cannot use the Comparison Test to compare $\sum_{n=1}^\infty\frac{1}{n!}$ to $\sum_{n=1}^\infty\frac{1}{n}$.
  3. Explain why $\frac{1}{n!} \le \frac{1}{n(n-1)}$ for $n\ge 2$.
  4. Show that $\sum_{n=1}^\infty\frac{1}{n(n-1)}$, which is equal to $\sum_{n=1}^\infty\frac{1}{n^2-n}$, converges by comparing it to $\sum_{n=1}^\infty\frac{1}{n^2}$ with the LCT.
  5. What can you conclude about $\sum_{n=1}^\infty \frac{1}{n!}$? And why
[11.14.16] - Monday

Sections covered: 11.2 (finished)
Reading for next time: (Carry over from last time) 11.3. Focus on the following:
  1. The statement of the Integral Test on pg 721
  2. The (important) note between the statement of the Integral Test and Example 1 on pg 721
  3. Example 4
To discuss next time: (Carry over from last time)
  1. After reading Example 4, determine if $\displaystyle\sum_{i=0}^\infty \frac{n}{e^n}$ converges or diverges.
    • You will probably want to use the integral test, but to do this, make sure to explain why $\displaystyle\frac{x}{e^x}$ is continuous, positive, and (eventually) decreasing.
  2. Also, determine if $\displaystyle\sum_{i=0}^\infty \frac{-n}{e^n}$ converges or diverges.
Week 11
[11.10.16] - Thursday

Such a good day. Lot's of doing math and tons of excellent presentations!

- So clear! So great! Thanks to all of the presenters! -

Sections covered: 11.2 (continued)
Reading for next time: 11.3. Focus on the following:
  1. The statement of the Integral Test on pg 721
  2. The (important) note between the statement of the Integral Test and Example 1 on pg 721
  3. Example 4
To discuss next time:
  1. After reading Example 4, determine if $\displaystyle\sum_{i=0}^\infty \frac{n}{e^n}$ converges or diverges.
    • You will probably want to use the integral test, but to do this, make sure to explain why $\displaystyle\frac{x}{e^x}$ is continuous, positive, and (eventually) decreasing.
  2. Also, determine if $\displaystyle\sum_{i=0}^\infty \frac{-n}{e^n}$ converges or diverges.
[11.09.16] - Wednesday

Sections covered: 11.1 (finished), 11.2 (started)
Reading for next time: End of 11.2. Focus on the following:
  1. Theorem 6 through end of section. There is a lot of important information here!!!
To discuss next time:
  1. After reading examples 2-4 and the note in the margin next to $\fbox{4}$, try this variation: find the value of $c$ such that $\sum_{n=1}^\infty e^{nc} = 10$. Hint: $\sum_{n=1}^\infty e^{nc}$ is a geometric series. What is the common ratio?
  2. How would your answer change if the equation was $\sum_{n=0}^\infty e^{nc} = 10$?
  3. After reading Theorem 8 and Example 11, determine if the following series is convergent or divergent: \[\sum_{n=1}^\infty \frac{2^n+e^n}{\pi^n}\]
  4. Meditate on Theorem 8, and be able to explain why the following is true:

    If $\sum a_n$ is convergent and $\sum b_n$ is divergent, then $\sum (a_n + b_n)$ is divergent.

  5. Determine if the following series is convergent or divergent: \[\sum_{n=1}^\infty \frac{2^n+\pi^n}{e^n}\]
  6. Meditate on Theorem 8 again, and determine if the following is true or false:

    If $\sum a_n$ is divergent and $\sum b_n$ is divergent, then $\sum (a_n + b_n)$ is divergent.

[11.07.16] - Monday

Vote!!

Sections covered: 11.1 (continued)
Reading for next time: 11.2. Focus on the following:
  1. Intro through Example 4
  2. The comment in the margin next to box $\fbox{4}$ for the geometric series is very important.
To discuss next time:
  1. After reading examples 2-4 and the note in the margin next to $\fbox{4}$, try this variation: find the value of $c$ such that $\sum_{n=1}^\infty e^{nc} = 10$. Hint: $\sum_{n=1}^\infty e^{nc}$ is a geometric series. What is the common ratio?
  2. How would your answer change if the equation was $\sum_{n=0}^\infty e^{nc} = 10$?
Week 10
[11.04.16] - Friday

Sections covered: 11.1 (continued)
Reading for next time: Section 11.1. Focus on the following:
  1. Box $\fbox{9}$ and Definition $\fbox{10}$
  2. Examples 9-13 (Example 10 is important!)
To discuss next time: working with factorials. (Make sure to read Example 10 first.)
  1. Consider the sequence $\left\{\frac{n!}{2^n}\right\}$.
    • Write out $a_1$, $a_2$, $a_3$, and $a_n$ without simplifying (as in Example 10)
    • Try to group the terms in your unsimplified expression for $a_n$, and explain why $a_n > \frac{n}{4}$. This is slightly subtle; take your time.
    • Explain why the sequence $\left\{\frac{n!}{2^n}\right\}$ diverges (to infinity).
  2. Consider the sequence $\left\{\frac{(2n)!}{(2n+2)!}\right\}$.
    • Write out $a_1$, $a_2$, $a_3$, and $a_n$ without simplifying (as in Example 10)
    • Try to group the terms in your unsimplified expression for $a_n$, and explain why $a_n = \frac{1}{(2n+2)(2n+1)}$.
    • Explain why the sequence $\left\{\frac{(2n)!}{(2n+2)!}\right\}$ converges (to 0).
[11.03.16] - Thursday

Started sequences and series today - hooray!

Sections covered: 10.4 (finished), 11.1 (started)
Reading for next time: Section 11.1. Focus on the following:
  1. Theorem 3 and the limit laws on page 697
  2. Examples 4-7
To discuss next time: the worksheet from class today. Keep working through it, and come with questions.
[11.02.16] - Wednesday

Talked about area in polar, and started arc length. On to sequences and series tomorrow.

Also, Jullien Gordon will be speaking on campus tomorrow (during the 12pm class ☹). You should definitely consider going if you can. There is more information here: theuniversityunion.com/unique/event/jullien-gordon

Sections covered: 10.4 (almost finished)
Reading for next time: Section 11.1. Focus on the following:
  1. Introduction through Example 3
  2. Definition 1
To discuss next time: just come prepared for group work.
[10.31.16] - Monday

Hearts and roses.

Sections covered: 10.3 (finished), 10.4 (started)
Reading for next time: Section 10.4. Focus on the following:
  1. Examples 1 through 3
To discuss next time: Consider the polar curve $r = 1+2\sin\theta$
  1. Try to graph it yourself. Check yourself on Desmos.
  2. Find all values for $\theta$ for which the curve goes through the origin (i.e. when $r=0$)
  3. Set up an integral that computes the area of the inner loop of the curve.
Week 9
[10.28.16] - Friday

Circles and hearts.

Sections covered: 10.3 (continued)
Reading for next time: Section 10.4. Focus on the following:
  1. Introductions through Example 1
To discuss next time: Repeat from last time: think more about the polar equation $r=\frac{\pi}{\theta}$.
  1. Graph it on Desmos, and study what happens when $\theta \rightarrow 0^+$.
  2. There seems to be a horizontal asymptote. Can you confirm this? Hint: you want to study what happens to the $y$-values as $\theta \rightarrow 0^+$, i.e. you want to study $\displaystyle\lim_{\theta \rightarrow 0^+} y$. Remember that (always) $y=r\sin\theta$ and that for this problem you have $r=\frac{\pi}{\theta}$. Combine this all together, and take the limit.
  3. Use what you read in the section to compute $\displaystyle\frac{dy}{dx}$ for this curve. You should get an expression in terms of $r$ and $\theta$. Now compute $\displaystyle\lim_{\theta \rightarrow 0^+} \frac{dy}{dx}$. Does this support what you found before?
  4. And what is happening with the graph when $\theta$ is negative? (Careful: Desmos is not showing you this!) Do you notice any symmetry?
[10.27.16] - Thursday

On to polar.

Sections covered: 10.2 (finished), 10.3 (started)
Reading for next time: Section 10.3. Focus on the following:
  1. The subsection "Tangents to Polar Curves" on pg 663
  2. Example 9
To discuss next time: Think more about the polar equation $r=\frac{\pi}{\theta}$.
  1. Graph it on Desmos, and study what happens when $\theta \rightarrow 0^+$.
  2. There seems to be a horizontal asymptote. Can you confirm this? Hint: you want to study what happens to the $y$-values as $\theta \rightarrow 0^+$, i.e. you want to study $\displaystyle\lim_{\theta \rightarrow 0^+} y$. Remember that (always) $y=r\sin\theta$ and that for this problem you have $r=\frac{\pi}{\theta}$. Combine this all together, and take the limit.
  3. Use what you read in the section to compute $\displaystyle\frac{dy}{dx}$ for this curve. You should get an expression in terms of $r$ and $\theta$. Now compute $\displaystyle\lim_{\theta \rightarrow 0^+} \frac{dy}{dx}$. Does this support what you found before?
  4. And what is happening with the graph when $\theta$ is negative? (Careful: Desmos is not showing you this!) Do you notice any symmetry?
[10.26.16] - Wednesday

So happy to get back to the discussions - great day with great presentations!

Sections covered: 10.2 (almost finished)
Reading for next time: Section 10.3. Focus on the following:
  1. Introduction
  2. Examples 1, 4, 5, 7
To discuss next time:
  1. Play around with polar equations in Desmos. Look at the following for examples:
  2. Use Desmos to make a super cool graph using a polar equation. Write everything down, so you can reproduce it in class. (I'll make sure we have time to share some of these this time!)
  3. Graph the polar equation $r=\frac{\pi}{\theta}$. Think about what $r$ and $\theta$ represent and be able to explain why the graph looks like it does. Make sure you zoom in enough to see the spiral and zoom out enough to see that it does not continue to spiral. Also, Desmos has a hard time when you zoom in - it should keep spiraling. Try looking at the following graph (on WolframAlpha):
    http://www.wolframalpha.com/input/?i=polar+plot+r+%3D+1%2Fθ,+1+%3C+θ+%3C+500
[10.24.16] - Monday

More calculus with parametric equations

Sections covered: 10.2 (continued)
Reading for next time: Section 10.2. Focus on the following:
  1. Subsections on area and arc length.
  2. Example 5
To discuss next time: Consider the curve $\mathcal{C}$ defined by the parametric equations \[\begin{align*}x=& t^3-3t\\ y=& 3t^2-9\end{align*}\] This is the same one that was on the last worksheet and was discussed at the beginning of class today.
  1. If you need to, check out the graph of $\mathcal{C}$ here https://www.desmos.com/calculator/x7cia8bdpz. The graph also illustrates tangent lines.
  2. Find the area of the "teardrop" at the bottom of $C$. Hint: to find the area between a parametric curve $x=f(t)$, $y=g(t)$, $\alpha\le t\le \beta$, and the $x$-axis, the book gives the formula $\int_\alpha^\beta g(t)f'(t)\;dt$. Here it might be better to find the area between the curve and the $y$-axis (and multiply by 2), and for this, the formula is $\int_\alpha^\beta f(t)g'(t)\;dt$
Week 8
[10.21.16] - Friday

Group work on parametric equations.

Sections covered: 10.2 (started)
Reading for next time: None.
To discuss next time: None.
[10.20.16] - Thursday

Midterm.

Sections covered: Midterm
Reading for next time: None. Relax.
To discuss next time: None. Relax.
[10.19.16] - Wednesday

Hope you had a good review of integration in class today. I missed you all!

- Asia (over there - across the river) wishes you lots of luck on the exam. And so do I!! -

Sections covered: Exam Review
Reading for next time: None. Study.
To discuss next time: None. Study.
[10.17.16] - Monday

Kept on with the parametric and got started reviewing for the midterm.

Sections covered: Section 10.1 (continued)
Reading for next time: None. Study.
To discuss next time: None. Study.
Week 7
[10.14.16] - Friday

Got a little slowed down by the geometry of cones today ☺, but still had some time to think about different ways of representing a collection of points. There was a nice balance in the class of those that found a function to represent the data (e.g. $y=\sqrt{x} + 1$ or $x = (y-1)^2$) and those that found parametric equations to represent the data (e.g. $(x,y) = (n^2,n+1)$). Nice job everyone! And a special thanks to the one that went to the board; it was super clear, detailed, and, of course, right on!

Sections covered: Section 8.2 (finished), Section 10.1 (started)
Reading for next time: (This is a repeat of last time, so if you already did it, focus on studying for the exam.)
Section 10.1. Focus on the following:
  1. Introduction
  2. Examples 1, 2, 4
To discuss next time: (This is a repeat of last time, so if you already did it, focus on studying for the exam.)
  1. Play around with parametric equations in Desmos. Look at the following for examples:
  2. Use Desmos and what you learned in Example 4 to do problem 35 on page 647 of the textbook. Write everything down on paper, so you can reproduce it in class. Hint: each part of the picture will be represented by a different set of parametric equations.
  3. Use Desmos to make a super cool graph using parametric equations. Write everything down on paper, so you can reproduce it in class.
[10.13.16] - Thursday

Sections covered: Section 8.2 (continued)
Reading for next time: Section 10.1. Focus on the following:
  1. Introduction
  2. Examples 1, 2, 4
To discuss next time:
  1. Play around with parametric equations in Desmos. Look at the following for examples:
  2. Use Desmos and what you learned in Example 4 to do problem 35 on page 647 of the textbook. Write everything down on paper, so you can reproduce it in class. Hint: each part of the picture will be represented by a different set of parametric equations.
  3. Use Desmos to make a super cool graph using parametric equations. Write everything down on paper, so you can reproduce it in class.
[10.12.16] - Wednesday

Finished up arc length, and then started surface area by showing that Gabriel's Horn has an infinite surface area (but finite volume)!

Sections covered: Section 8.1 (finished), Section 8.2 (started)
Reading for next time: Section 8.2. Focus on the following:
  1. The blue boxes labeled $\fbox{4}$ up through $\fbox{8}$
  2. Examples 2-3
To discuss next time: Revisit the Gabriel's Horn example (included below) from last time, and carefully write out your justification for the comparison test. (Be prepared to share.)
  1. Set up an integral that computes the surface area of Gabriel's Horn. (Recall that Gabriel's Horn is the solid obtained by revolving the graph of $y=\frac{1}{x}$, from $x=1$ to $\infty$, about the $x$-axis.)
  2. Show that the integral diverges. Hint: you can try to directly evaluate the integral if you want, but a comparison test with $\int_1^\infty \frac{1}{x}\,dx$ should be much easier.
[10.10.16] - Monday

Arclength today. Many thanks to those who came prepared today and many$^2$ thanks to those that went to the board.

Sections covered: Section 8.1 (started)
Reading for next time: Section 8.2. Focus on the following:
  1. Introduction through the blue box labeled $\fbox{4}$
  2. Example 1
To discuss next time:
  1. Set up an integral that computes the surface area of Gabriel's Horn. (Recall that Gabriel's Horn is the solid obtained by revolving the graph of $y=\frac{1}{x}$, from $x=1$ to $\infty$, about the $x$-axis.)
  2. Show that the integral diverges. Hint: you can try to directly evaluate the integral if you want, but a comparison test with $\int_1^\infty \frac{1}{x}\,dx$ should be much easier.
Week 6
[10.07.16] - Friday

Finally wrapped up improper integrals.

Sections covered: Section 7.8 (finished)
Reading for next time: Section 8.1. Focus on the following:
  1. Introduction through Example 2
To discuss next time:
  1. Set up an integral to compute the length of $y=\sin(x)$, $0\le x\le 2\pi$. Can you evaluate this integral? If you can, do it; otherwise, estimate it using a Riemann sum (with not too many rectangles).
  2. Set up an integral to compute the length of $y=\ln|\cos(x)|$, $0\le x\le \frac{\pi}{3}$. Can you evaluate this integral? If you can, do it; otherwise, estimate it using a Riemann sum (with not too many rectangles).
[10.06.16] - Thursday

Continued making our way through improper integrals. We had several excellent, and highly productive failures in both classes. Many thanks to all those involved!! Unfortunately, I only got a picture of a nonfailure, which nevertheless was also productive ☺

- Crushed. Completely. -

Sections covered: Section 7.8 (continued)
Reading for next time: Review the solution in the above picture, and note any questions you have.
To discuss next time: Nothing new. Study for the quiz.
[10.05.16] - Wednesday
Sections covered: Section 7.8 (continued)
Reading for next time: End of Section 7.8. Focus on the following:
  1. Examples 5-7
  2. The Warning right after Example 7
To discuss next time:
  1. True or False: $\displaystyle\int_{-1}^1 \frac{1}{x^3}\,dx = 0$. Explain.

  2. True or False: $\displaystyle\int_{-1}^1 \frac{1}{\sqrt[3]{x}}\,dx = 0$. Explain.
[10.03.16] - Monday

- Trig. sub. and I.P (and rainbows) - Love it! -

Sections covered: Section 7.8 (started)
Reading for next time: Section 7.8. Focus on the following:
  1. Examples 1-4
To discuss next time: your feelings about the fact that $\int_1^\infty \frac{1}{x}\,dx$ is infinite while $\int_1^\infty \frac{1}{x^2}\,dx$ is finite. Really, how do you feel? Surprised, happy, sad, lied to, indifferent?
Week 5
[09.30.16] - Friday

Had a fun day of group work with many excellent presentations (though, if you ask me, there were not enough mistakes ☺). Nice job solving hard problems! We'll finish presenting the problems on Monday. Happy Friday!

- "Ugly" integrals and pretty colors -

Sections covered: Integration review.
Reading for next time: Section 7.5. Focus on the following:
  1. Everything! (It's a review of the integration techniques we've covered in Chapter 7.)
To discuss next time:
  1. Take a look at the last two group work problems, if you haven't already. Here they are:
    • Compute \[\int \frac{\sqrt{1+\sqrt{x}}}{x}\,dx.\]
    • Compute \[\int \frac{x\ln x}{\sqrt{x^2-1}}\,dx.\]
  2. Meditate (again) on the next question. (And, be careful!)

    True or False: $\displaystyle\int_{-1}^1 \frac{1}{\sqrt[3]{x}}\,dx = 0$. Explain.

[09.29.16] - Thursday

More partial fraction decompositions. We'll finally wrap this up tomorrow with you all working through a few more examples.

Sections covered: 7.4 (continued).
Reading for next time: None. Focus on the homework.
To discuss next time:
  1. Continue to think about this one form last time: using what you read (in Example 9), try to compute \[\int \frac{1}{x^2+x\sqrt{x}}\;dx.\] Hint: as in Example 9, you want to start with a $u$-sub. that will turn the integrand into a rational function. Make a similar choice as in Example 9.
  2. As a hook into our next topic, meditate on the next question. (And, be careful!)

    True or False: $\displaystyle\int_{-1}^1 \frac{1}{\sqrt[3]{x}}\,dx = 0$. Explain.

[09.28.16] - Wednesday

Kept working on partial fraction decompositions. More to come...

Sections covered: 7.4 (continued).
Reading for next time: End of Section 7.4. Focus on the following:
  1. Examples 7-9
To discuss next time:
  1. Be prepared to write out the form of the partial fraction decomposition (as in Example 7) for any big, nasty rational function, but you can assume that the denominator will be easy to factor.
  2. Using what you read (in Example 9), try to compute \[\int \frac{1}{x^2+x\sqrt{x}}\;dx.\] Hint: as in Example 9, you want to start with a $u$-sub. that will turn the integrand into a rational function. Make a similar choice as in Example 9.
[09.26.16] - Monday

Wrapped up trig. substitution today and got started with partial fractions. We had several excellent presentations (but unfortunately ran out of time in both classes)! We'll definitely revisit these at the beginning of Wednesday.

- Slaying partial fractions at 10AM! -

- With some small typos corrected - the final answer should also have a swap. (My apologies for rushing the speaker!! I take full responsibility for the typos.) -

- Round 2 at noon -

- Success again! -

Sections covered: 7.3 (finished), 7.4 (started).
Reading for next time: Section 7.4. Focus on the following:
  1. Reread Example 2
  2. Example 3
To discuss next time: Nothing new, but make sure to review this one from before:
  1. Using what you read in 7.4, try to compute \[\int \frac{x+7}{x^2+x-6}\;dx.\] Here are some steps to follow:
    • Factor $x^2+x-6$ as $x^2+x-6 = (x+3)(x-2)$
    • Write \[\frac{x+7}{x^2+x-6} = \frac{A}{x+3} + \frac{B}{x-2},\] and use the ideas in Example 2 to solve for $A$ and $B$.
    • Now evaluate $\int \frac{x+7}{x^2+x-6}\;dx$ by instead evaluating \[\int \frac{A}{x+3} + \frac{B}{x-2}\;dx.\]
Week 4
[09.23.16] - Friday

More trig. substitution today. Thanks for all of the help at the board!

- End game. -

Sections covered: 7.3 (continued).
Reading for next time: Section 7.4. Focus on the following:
  1. Introduction through Example 2
To discuss next time:
  1. You know how to compute $\int \frac{1}{x-6}\;dx$, right?
  2. Using what you read in 7.4 (Example 1), compute \[\int \frac{x^2+x+1}{x-6}\;dx.\] If you need to review long division of polynomials, try this Khan Academy video: https://www.khanacademy.org/math/algebra2/arithmetic-with-polynomials/long-division-of-polynomials/v/dividing-polynomials-1
  3. Remember how to compute $\int \frac{4x+2}{x^2+x-6}\;dx$? Hint: basic substitution.
  4. Using what you read in 7.4, try to compute \[\int \frac{x+7}{x^2+x-6}\;dx.\] Here are some steps to follow:
    • Factor $x^2+x-6$ as $x^2+x-6 = (x+3)(x-2)$
    • Write \[\frac{x+7}{x^2+x-6} = \frac{A}{x+3} + \frac{B}{x-2},\] and use the ideas in Example 2 to solve for $A$ and $B$.
    • Now evaluate $\int \frac{x+7}{x^2+x-6}\;dx$ by instead evaluating \[\int \frac{A}{x+3} + \frac{B}{x-2}\;dx.\]
[09.22.16] - Thursday

CarTalked, yet again, today. We had very nice presentations in both classes, and finally, with the help of a lot of trig., found an antiderivative for $\sqrt{100 - x^2}$.

Sections covered: 7.3 (started).
Reading for next time: None.
To discuss next time: Try to do the integral that we ended with by following the following steps. (Yes, this one is in the book, but try not to peek.) The integral was \[\int \frac{1}{x^2\sqrt{x^2+4}}\,dx.\]
  1. Make the substitution $x = 2\tan\theta$ (as was mentioned in class). Don't forget to substitute in for $dx$ too.
  2. Go through the steps to simplify the resulting integral to the form \[\frac{1}{4}\int\frac{\cos\theta}{\sin^2\theta} \,d\theta\]
  3. Evaluate the integral. (Hint: try a $u$-sub.) You should end up with \[-\frac{1}{4\sin \theta} + C\]
  4. Build a triangle for $x = 2\tan\theta$ and substitute to get the integral back in terms of $x$.
[09.21.16] - Wednesday

Exam today. I'll do my best to have it graded quickly.

Sections covered: None.
Reading for next time: Section 7.3. Focus on the following:
  1. The introduction
  2. Examples 1 and 2
To discuss next time: CarTalk! If you remember, the CarTalk problem reduced to solving the following equation for $a$: \[\int_0^a\sqrt{100 - x^2}\,dx = \frac{25\pi}{2}.\] We could estimate this, but we didn't know how to compute it directly because we didn't know an antiderivative for $\sqrt{100 - x^2}$. Use what you read in Section 7.3 to compute $\int \sqrt{100 - x^2}\, dx$.
[09.19.16] - Monday

More trig. fun today, and a little review for the first midterm. Good luck with your studying! (Remember that the first midterm will be Wednesday. It'll cover up through section 7.1.)

Sections covered: 7.2 (finished)
Reading for next time: None. Focus on preparing for the exam.
To discuss next time: Focus on preparing for the exam.
  1. Make sure you understand all of the WebAssign problems that you've done. You can look back at each problem to see the answer and a solution if you want.
  2. Review the Written Homework problems too. Feel free to talk with me about them, but answers and solutions can also be found on Slader.com.
  3. Finally, look over the discussion questions. These should reinforce the concepts and are, of course, always fair game to put on an exam.
Week 3
[09.16.16] - Friday

Had some fun with trig. today. There will be lots more to come! I promise ☺

Remember that the first midterm will be next Wednesday. It will cover up through section 7.1.

Sections covered: 7.1 and the beginning of 7.2
Reading for next time: Section 7.2. Focus on the following:

  1. Examples 5-7
To discuss next time: Let's start reviewing for the exam. Meditate on the following questions, and be prepared to share your answers (especially those who have not presented yet).
  1. What is an example of a problem that you still find challenging, and what specifically do you find challenging about it? For example, is it the visualization, the set up, the integration,...
  2. What is an example of a problem that you have worked hard to understand, and what specifically do you think is the key to understanding the problem?
[09.15.16] - Thursday

Sections covered: 7.1 (finished, mostly)
Reading for next time: None. Focus on studying for the quiz.
To discuss next time: Focus on studying for the quiz. In other words, focus on understanding (not just finishing) the written homework for tomorrow.
[09.14.16] - Wednesday

Sections covered: 7.1 (started)
Reading for next time: Section 7.1 continued. Focus on the following:

  1. Examples 4 and 5
To discuss next time: Meditate (again) on the discussion question from last time about the volume of the solid obtained by revolving the region bounded by $y=e^x$, $y=0$, $x=0$, and $x=1$ about the $y$-axis. Remember what the integral looked like if you use washers instead of shells? You have to integrate $(\ln(x))^2$. Can you? That is, be ready to discuss how to compute $\int (\ln(x))^2 \,dx$. Make sure you come prepared to talk about what you tried even if you can't finish the problem.
[09.12.16] - Monday

Sections covered: 6.3
Reading for next time: Section 7.1. Focus on the following:

  1. the introduction and formula for integration by parts, i.e. everything before Example 1
  2. Examples 1, 2, 3
To discuss next time: Finish the example started at the end of class. Find the volume of the solid obtained by revolving the region bounded by $y=e^x$, $y=0$, $x=0$, and $x=1$ about the $y$-axis. Hint: graph it and decide what seems easier to you: shells or washers. Or maybe they both seem hard. (No need to do it the way I chose.) And now the real hint: you will likely need to use integration by parts to finish things off.
Week 2
[09.09.16] - Friday

Wrapped up volumes by disks/wahers today, and found out that Gabriel's Horn, which has an infinite length, holds a finite volume of $\pi$

Sections covered: 6.2 (finished)
Reading for next time: Continue 6.3. Focus on the following:

  1. The intro. to 6.3 (again) paying special attention to the pictures in Figure 3
  2. Examples 1 and 2
To discuss next time: Nothing formal.
[09.08.16] - Thursday

Talked more about volumes today, but ran out of time for Gabriel's Horn. We'll do it first thing tomorrow.

Sections covered: 6.2 (almost finished)
Reading for next time: Finish 6.2 and start 6.3. Focus on the following:

  1. Examples 6 in 6.2
  2. The intro. to 6.3 up through Example 1
To discuss next time: Can you find the volume of Gabriel's Horn? Gabriel's Horn is the solid obtained by revolving the graph of $y=\frac{1}{x}$, from $x=1$ to $\infty$, about the $x$-axis. Hint: first find the volume of the horn from $x=1$ to $x=a$, and then take the limit as $a\rightarrow \infty$. Be prepared to present a picture and explain the the integral that you came up with, as well as the limit.
[09.07.16] - Wednesday

Dissected eggplants today in the name of Mathematics and found their volumes to (approximately be 288.7cm$^3$ and 249.52cm$^3$. Many thanks to all of those who participated!

- And now we know. -

Sections covered: 6.2 (started)
Reading for next time: More of 6.2. Focus on the following:

  1. Examples 2-5 and the wrap up on page 443.
To discuss next time: Can you find the volume of Gabriel's Horn? Gabriel's Horn is the solid obtained by revolving the graph of $y=\frac{1}{x}$, from $x=1$ to $\infty$, about the $x$-axis. Hint: first find the volume of the horn from $x=1$ to $x=a$, and then take the limit as $a\rightarrow \infty$. Be prepared to present a picture and explain the the integral that you came up with, as well as the limit.
Week 1
[09.02.16] - Friday

Talked (mostly me ☹)a bit more about areas today, and had a couple of brave souls in both sections share their work with the class. All were great and most came with a touch of productive failure, which I love! Bonus Points!

Sections covered: 6.1 (almost finished)
Reading for next time: Section 6.2. Focus on the following:

  1. Introduction through Example 1
To discuss next time: Given a ruler, a calulator, and a knife, can you find a good estimate of the volume of a zucchini? Be prepared to demonstrate.
[09.01.16] - Thursday

Wrapped up our review of Section 5.2 today, as well as the CarTalk problem, for now. But we (and Rich) are still waiting for an actual estimate...anyone?

Sections covered: Section 5.2 (finished)
Reading for next time: Nothing new. Focus on cleaning up your homework for tomorrow. That is, even if you "got the answers," make sure that everything is written up cleanly and is fully justified. Of course, you can always read more of 6.1 or get into 6.2.
To discuss next time: Again, just focus on the homework this time.
[08.31.16] - Wednesday

I really enjoyed the CarTalking today! Thanks to everyone, especially those who presented their ideas at the board and those who commented from the audience. I'm looking forward to hearing from even more of you tomorrow!

Reading for next time: Section 6.1. Focus on the following:
  1. the introduction through formula 2, and
  2. Examples 2, 6, and 7.
To discuss next time: CarTalk again: where should Rich from the CarTalk Problem mark for 3/4 of a tank of gas? Focus on trying to reformulate the problem in terms of a definite integral and, of course, try to "solve" the problem, i.e. make as good of an estimate as you can as to where the 20 inch stick should be marked for 3/4 of a tank of gas.
[08.29.16] - Monday - First day!

It was great to meet you all today. Thanks for all of the participation! (But a few of you still owe me a spirit animal...) See you Wednesday!

- Math Skills. -

Reading for next time: Section 5.2 (and 5.1 if you need to fill in). You should have covered this in Calc 1, but it is very important to review it. Focus on the following:
  1. the definition of the definite integral, and
  2. the content in blue boxes, e.g. statements of theorems and properties of the definite integral.
To discuss next time: Where should Rich from the CarTalk Problem mark for 3/4 tank of gas? Hint: this is hard! The CarTalk clip can be found in the "Content" section of SacCT. Focus on drawing an accurate, and well-labeled picture for the problem. It is totally fine if you don't solve it, but make sure you can clearly explain your approach and where you got stuck. Make sure to indicate if you used outside resources for parts of your solution, e.g. Desmos or WolframAlpha.