# Thread: Help evaluating Indefinite Integral (Calc. 1)

1. ## Help evaluating Indefinite Integral (Calc. 1)

I understand that I have to use u-substitution on one of the terms but I don't see which one.

I really have tried to solve this. I'm self-studying and hence have no real other recourse. I have searched the forum/google for similar problems but to no avail. Thanks and hello.

$\displaystyle \int\frac{x\sin\sqrt{2x^2-5}}{\sqrt{2x^2-5}}dx$

2. Originally Posted by nnnnnnnnnnnnnnnnnn
I understand that I have to use u-substitution on one of the terms but I don't see which one.

I really have tried to solve this. I'm self-studying and hence have no real other recourse. I have searched the forum/google for similar problems but to no avail. Thanks and hello.

$\displaystyle \int\frac{x\sin\sqrt{2x^2-5}}{\sqrt{2x^2-5}}dx$
Here it is useful to be able to spot that you have a function of the form:

$\displaystyle \displaystyle \frac{d}{dx}g(f(x))=f'(x)g'(f(x))$, so:

consider the derivative of $\displaystyle \cos(\sqrt{2x^2-5})$

CB

3. I see it now. Thanks, CaptainBlack!