some math help

Originally Posted by JaWiB

I thought f(x) at c doesn't have to exist for lim f(x) x->c to exist. Like:
f(x) = (x^2+x-2)/(x-1)

lim f(x) x->1 = 3 right?

Yes you can get it by manipulation or by L'Hopital.
Lim f'(x) when x->1 = lim 2x + 1 = 3.

Actually his assertion is correct. The form is indeterminate. L'Hopital can only be used on indeterminate forms.