# Thread: [SOLVED] Integration difficulty

1. ## [SOLVED] Integration difficulty

I can't get my head round this one:

int (1/x^2)*e^(1/x^2)

I know I need to use substitution but if I use u=1/x the derivative doesn't seem to help and the same if I use u=1/x^2

Any help appreciated

2. Originally Posted by bellycan
I can't get my head round this one:

int (1/x^2)*e^(1/x^2)

I know I need to use substitution but if I use u=1/x the derivative doesn't seem to help and the same if I use u=1/x^2

Any help appreciated
Let $t=1/x$ then,
$-\int e^{t^2}dt$

Which is not "doable".

3. ## is it a definite integral

Originally Posted by bellycan
I can't get my head round this one:

int (1/x^2)*e^(1/x^2)

I know I need to use substitution but if I use u=1/x the derivative doesn't seem to help and the same if I use u=1/x^2

Any help appreciated

if you have 0 to infinity as limits you might end up with the gamma integral
after suitable substitutions