# Math Help - Integration by Substitution!

1. ## Integration by Substitution!

I don't know which of the factores to pick out as the "u"

1. integral of e ^x/2

2. integral of ln4xdx/x

thanks!

2. Originally Posted by littlesohi
I don't know which of the factores to pick out as the "u"

1. integral of e ^x/2

2. integral of ln4xdx/x

thanks!
1. $u = \frac{x}{2}$

2. $u = \ln 4x$