If your function is: then this isn't in the form of 0/0 or infinity/infinity and therefore you can't use L'Hopital's rule.
I'm having a difficulty differentiating this using L'Hospital's rule:
lim x->(infinite) xsin(pi/x)
Applying L'Hospital's rule and differentiating I got:
lim x->(infinite) xcos(pi/x) + sin(pi/x)
and that equals = (infinite)(1) + 0 = infinite
The correct answer in my textbook is just "pi"
Can someone tell me what I'm doing wrong?