Is limit of function -1/0 ok? A quick question, i'm determining the limit of this function:
$$\lim_{x→1}\frac{x^2 - 2x}{x^2 -2x +1}$$
When I divide numerator and denominator by $x^2$ and fill in $1$, I get $-1/0$. This is an illegal form right? Or does it indicate it is going to $∞$ or $-∞$? 

Notice, $$\lim_{x\to 1}\frac{x^2-2x}{x^2-2x+1}$$
$$\lim_{x\to 1}\frac{(x^2-2x+1)-1}{x^2-2x+1}$$
$$=\lim_{x\to 1}\left(1-\frac{1}{(x-1)^2}\right)\longrightarrow \color{red}{-\infty}$$
