# integral evaluation help

#### lethalasian

##### New member
integral e^x / sqrt(1-e^(2x)) DX

The chapter I am on is strategies for integration.

Would I substitute e^x = U
and then go on to do (1-u^2) using trig substitution?
I am stuck on this question any help would be appreciated

#### pka

##### Elite Member
This is rather straightforward. We get $$\displaystyle\int {\frac{1}{{\sqrt {1 - {u^2}} }}du = \arctan (u)}$$

#### Jomo

##### Elite Member
You need to be complete. If u =e^x, then du =e^xdx.

This yields the integral posted by pka which is supposed to be known to you.

Last edited:

#### topsquark

##### Full Member
You need to be complete. If u =e^x, then du =e^dx.

This yields the integral posted by pka which is supposed to be known to you.
aka $$\displaystyle du = e^x ~ dx$$

-Dan