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

#### naspek

$$\int{\left(\frac{x}{x^2 + 1}\right)\,dx}$$

how to integrate?
i know $$\int{\left(\frac{1}{x^2 + 1}\right)\,dx}$$
is tan^-1 x + C

how am i going to start answering this question
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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#### rock.freak667

Homework Helper
Re: Integration

try substituting u=x2+1, du=?

#### naspek

Re: Integration

try substituting u=x2+1, du=?
meaning.. i should u integration by substitution?

#### Bohrok

Re: Integration

Yes, try the u substitution.

#### naspek

Re: Integration

got it..
1/2 ln |x^2 + 1| + C

correct?

#### Bohrok

Re: Integration

That's right. One thing though: since x2 + 1 is always greater than 0, no absolute values are needed.

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

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