limit using l'hopitals rule

magnifik

1. The problem statement, all variables and given/known data
Find the limit as x goes to 1 of tan(pi*x/2)lnx


2. Relevant equations
using l'hopitals, lim f'(x)/g'(x)=answer


3. The attempt at a solution
i tried integrating by making the tangent part squared so i can divide by the tangent part, but i keep getting stuck. i think the answer is either 1 or infinity.

help please? thanks

Dick

I really don't know how you are trying to do the problem. l'Hopital's rule doesn't tell you to integrate anything. Write it as ln(x)/cot(pi*x/2). Now it's a 0/0 form. Now differentiate numerator and denominator like l'Hopital says.

magnifik

woops i meant taking the derivative

Mark44

Integrating has nothing to do with this problem. Try rewriting your limit as
[tex]\lim_{x \to 1}\frac{ln(x)}{cot(x*\pi/2)}[/tex]

Now you have something you can use L'Hopital's Rule on.