# L'hopital's rule confusion

1. Oct 28, 2011

### Lucy Yeats

I understand the use of this rule for the limit as x goes to 0, but not for the limit as x goes to infinity. Can this rule be used to find limits to infinity? How?

I have googled this but couldn't find a good explanation.

2. Oct 28, 2011

### AlephZero

You can substitute u =1/x, and find the limit as u goes to 0.

3. Oct 28, 2011

Thanks!