Answer
does not exist
Work Step by Step
$\lim\limits_{x \to 5}\frac{x^2-5x+6}{x-5}=\frac{(5)^2-5(5)+6}{(5)-5}=\frac{0}{0}=$indet
so we have to do algebra
$\lim\limits_{x \to 5}\frac{x^2-5x+6}{x-5}=\lim\limits_{x \to 5}\frac{(x-3)(x-2)}{(x-5)}$
We can't simplify or do anything further so the limit does not exist.