# WebWork Discussion

If anyone has WebWork questions, you can use the OpenLab to discuss them with one another. Click the plus sign at the top of the screen to submit a new post. Click the category “Discussion” on the right-hand side before you publish it, and the post will appear under the “Discussion” tab of the main page. You can then comment on these posts (though new commenters’ comments may require approval from the administrator–me–before they appear).

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### 22 Responses to WebWork Discussion

1. Jiamin Lu says:

Hello, Professor,
I just checked my mailbox.I received an email from you, but I can’t open it. Can you send another one about the instructions of how to log in Webwork website! Thank you.

• Kate Poirier says:

Hi Jiamin. I just sent you another email. Let me know if you’re still having trouble.

2. Diego says:

Guys, for f'(x)=cos(2x) we have to do the chain rule to figure out the derivative of the whole function f(x) right?? im struggling.

3. Diego says:

Guys, to find the derivatives of the function f(x)=cos(2x) we have to use the chain rule, right? and keep using it for f”(x), f”'(x), and so on…..?

• Kate Poirier says:

Hi Diego. Any time you’re differentiating a function which is a composition of functions, you’ll have to use the chain rule. It’s quite common for the derivative of a composition to involve a compositions, in which case you’d apply the chain rule each time you differentiate.

4. Ayoola Obi says:

I entered the right answer and it is still saying i am wrong i even preview it to see how the program is reading it and it is right. What is going on?

5. Jia Peng says:

Hi, professor.
I have trouble with the webwork (Taylor Series) i don’t understand what is asking me to find like (Find the first five non-zero terms of Taylor series centered at x = 5 for the function below. f(x)=ln(x). ) can u explain what this want me to find? thank you.

• Kate Poirier says:

Hi Jia Peng. Remember that the Taylor series of a function f(x) centered at x=a is *sort of* like a Taylor polynomial of infinite degree. If none of the first five terms of this Taylor series are zero, then you’ll just be finding the degree 4 Taylor polynomial for f(x)=ln(x) at x=5. If any of the first five terms of this Taylor series are zero, then you’ll be finding a higher-degree Taylor polynomial for f(x) = ln(x) at x=5…this is because the question is asking for the first five terms which are not zero. Hope that helps!

6. Syed says:

I was looking at chapter 10.7 in the textbook and i saw a section on Binomial series. I don’t think we did it in class just wondering if it will be on the test.

• Kate Poirier says:

Hi Syed. The topics from the textbook that may appear on the test are the ones that appear in the textbook homework on the syllabus, those that appear in WebWork exercises, and those that appear on the final exam review sheet.

• Yong says:

Also, in the homework, there are questions about the error bound. Will that also be covered in the exam? Because we haven’t discuss about it in class, I’m in doubt whether or not this will be on our test.

7. Jia Peng says:

Hi Proffesor.
i have trouble with the WebWork homework for trigonometric subtitution for question 10. integrate 4(1+s)/(s(s^2+5s+4))ds i can’t get the correct answer.

• Jia Peng says:

Ohhh i found my error i didn’t put the asb()…

8. Jia Peng says:

Hi professor.
I have a question for the Webwork improper integral for number 18 what does it mean by “For the values of p at which the integral converges, evaluate it. Integral =____” i got the answer for the other part but i just dont get this part.

• Jia Peng says:

also for question 20 the last part that said “Value of convergent integral =___”

and for question 22 last part that said “For the values of p at which the integral converges, evaluate it. Integral =___”

I have trouble getting those parts.

• Jia Peng says:

also for question 20 the last part that said “Value of convergent integral =___”

and for question 22 last part that said “For the values of p at which the integral converges, evaluate it. Integral =___”

I have trouble getting those parts.

• Kate Poirier says:

Hi Jia Peng,

You actually did the hard part for #18! You’ve said in the first part, that if p is between negative infinity and 1 (not including 1) then the integral from 0 to 1 of 1/x^p converges. If an integral converges, it converges to a number, which represents the area of the corresponding region. For example, if p=1/2, you can actually find that number evaluate the integral as a limit. For this question, you’re supposed to keep p general, not choose a particular example, but you can still evaluate the integral as a limit. Your answer will depend on p, which means you’re not looking for a number, but instead looking for a formula in the variable p. The way that you’ll find it is almost exactly the same as the way that you’d evaluate the integral if you had chosen a particular value for p.

Hope that helps!

• Kate Poirier says:

If you can figure out the second part for #18, I’m sure you’ll be able to figure out the second part for #22 too. The actual integration there looks like it could be a little more involved.

• Kate Poirier says:

#20 is a little different. You found the value of C for which the integral converges (to a number) in the first part. For the second part, you’ll use that value of C and then evaluate the integral (find that number), again as a limit.

• Jia Peng says:

ok got them. thank you!! C: