...Okay, so I don't understand what I'm doing wrong, so I need some help.
lim x->3 x^2+x-6 / x^2-9
I'm supposed to find the limit, which I can't figure out
straight substitution of x = 3 gets you 6/0 ... what does that tell you about the limit?
lim x->4- √x -2 / x-4
which is, again, finding the limit.
(√x -2)/(x-4) = (√x -2)/[(√x -2)(√x +2)]