# Thread: I need Calc Help!

1. ## I need Calc Help!

help?

2. Q:

Evaluate

$\int \frac{\sqrt{9-x^2}}{x^2} dx$

Try the change of variable:

$x=3\cos(u)$.

Which transforms the integral to:

$-\int \tan ^2(u) du =u-\tan(u)$,

if I have done this right, and from here bob's your uncle

RonL