- #1

- 438

- 0

## Homework Statement

evaluate [tex]\int \frac{1}{x^2+1} dx[/tex]

## Homework Equations

## The Attempt at a Solution

This cant be [tex]\frac{\ln x^2+1}{2x}[/tex] , my first thought on this .

Then , i tried partial fraction , it didn't work either .

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- Thread starter thereddevils
- Start date

- #1

- 438

- 0

evaluate [tex]\int \frac{1}{x^2+1} dx[/tex]

This cant be [tex]\frac{\ln x^2+1}{2x}[/tex] , my first thought on this .

Then , i tried partial fraction , it didn't work either .

- #2

Mark44

Mentor

- 35,132

- 6,878

Your first thought led you to try an ordinary substitution, u = x^2 + 1. This won't work, though, because du = 2xdx, so there's no way to change the given integrand to du/u.## Homework Statement

evaluate [tex]\int \frac{1}{x^2+1} dx[/tex]

## Homework Equations

## The Attempt at a Solution

This cant be [tex]\frac{\ln x^2+1}{2x}[/tex] , my first thought on this .

Then , i tried partial fraction , it didn't work either .

If you know a derivative formula for which d/dx(something) = 1/(x^2 + 1) then that will be helpful in this problem. If you don't know or don't remember such a formula, a trig substitution will be the way to go, with tan u = x/1.

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