# Math Help - What exactly is this question asking?

1. ## What exactly is this question asking?

I'm not too sure if I'm approaching the question correctly:

(a) Find $\frac {d}{dx} [\frac {-1}{\sqrt{1+x^2}}]$(b) Hence evaluate $\\ \int_0^2 {\frac{x}{(1+x^2)^\frac{3}{2}}}dx$

And this is my attempt:

(a)
Find $\frac {d}{dx} [\frac {-1}{\sqrt{1+x^2}}]$

$= \frac{2x}{2(x^2 +1)^\frac{3}{2}}$
(b) Hence evaluate $\int_0^2 {\frac{x}{(1+x^2)^\frac{3}{2}}}dx$

$=-\frac {1}{\sqrt{x^2 +1}}\\\\for 2\\=-\frac {1}{\sqrt{5}}\\\\for 0\\\\=-1\\\\=-\frac {1}{\sqrt{5}}-(-1)\\\\= 1-\frac {1}{\sqrt{5}} \approx 0.553$

Help much appreciated!

2. ## Re: What exactly is this question asking?

you are very right. In a way he has given the integral you just have to evaluate between the interval for the given interval.