## anonymous 5 years ago int_{0}^{3} x/(sqrt{x^2+16}

1. anonymous

let$x =\tan \theta$

2. anonymous

:) thx

3. anonymous

On closer inspection, you don't need trig sub, u sub would suffice. I never noticed until after I worked it out myself. But hey, good practice for trig sub. When you get it on the test you going to knock it out of the park.

4. amistre64

shouldnt x = 4tan(t)? that way; when you square it you get: sqrt(16 tan^2(t) + 16) = sqrt(16(tan^2+1))) = 4sec^2

5. amistre64

err.... 4 sec :)

6. anonymous

Yes. I think he picked that up.