# How to integrate int -1/(x^2 +1)^2 dx

#### cscott

1. Homework Statement

Find the following intergral...

2. Homework Equations

$$\int{\frac{-1}{(x^2+1)^2}dx}$$

3. The Attempt at a Solution

I can't get anywhere with this... any hints?

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#### bob1182006

sorry rushed the problem and did it wrong

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#### imranq

hint:

$$\frac{d}{{dx}}{\arctan{x}} = \frac{1}{x^2 +1}$$

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#### StatusX

Homework Helper
Try adding and subtracting x^2 in the numerator.

#### dextercioby

Make the substitution $x=\tan t$. You'll eventually get $\int \cos^2 t \ dt$ which is easy to do.