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Mathematics 23 Online
OpenStudy (precal):

FTC part 2 question

OpenStudy (precal):

If I don't use FTC part 2 to do the following question and just integrate then take the derivative, will I always get the correct solution

OpenStudy (precal):

I need to type the question, sorry, I thought I could upload it on my ipad

OpenStudy (precal):

d/dx integral x^3 to 3 function is (2-t^2)dt

OpenStudy (anonymous):

Yes, integrating and differentiated will get the correct answer.

OpenStudy (precal):

upper limit is x^3 and lower limit is 3

OpenStudy (precal):

Cool thanks. I will do it in that fashion

OpenStudy (anonymous):

For example: \[ \frac{d}{dx} \int\limits_{a}^{g(x)} f'(x)~dx= \frac{d}{dx} \bigg[f(g(x))-f(a)\bigg] = f'(g(x))g'(x) \]

OpenStudy (anonymous):

Well, putting the variable of integration in the limits is bad, so here is the correct way to write it: \[ \frac{d}{dt} \int\limits_{a}^{g(t)} f'(x)~dx= \frac{d}{dt} \bigg[f(g(t))-f(a)\bigg] = f'(g(t))g'(t) \]

OpenStudy (precal):

Ok Thanks, I am studying for a final exam and I am trying to do the problems in the way that makes sense to me. It makes sense to me to integrate then take the derivative

OpenStudy (zarkon):

\int\limits_{1}^{x^3}e^{t^2}dt

OpenStudy (precal):

Is this going to fail?

OpenStudy (zarkon):

\[\frac{d}{dx}\int\limits_{1}^{x^3}e^{t^2}dt\]

OpenStudy (anonymous):

Integrating it is difficult because the anti-derivative is not an elementary function.

OpenStudy (precal):

true and I would need to use u sub and I have u but not du

OpenStudy (anonymous):

You would have to do a Taylor series to integrate it, when in reality you don't have to integrate it to begin with.

OpenStudy (zarkon):

learning the theorem is the best thing to do

OpenStudy (precal):

I don't think my exam is on that level

OpenStudy (precal):

here I found another problem d/dx integral 0 to 3x^2 function is (t^2+4t ) dt

OpenStudy (precal):

just looking for the duct tape approach

OpenStudy (precal):

this one should work as well

OpenStudy (precal):

Thanks for your help

OpenStudy (anonymous):

The duct tape approach is to have some general anti-derivative and call it \(F\) because once you differentiate it, it will go away.

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