I'd like to evalute the limit of: $\lim\limits_{h\to 0}\frac{\quad\frac{1}{(x+h)^2} - \frac{1}{x^2}\quad}{h}.$
if it exists. What throws me off is that there is another variable (x). How do I approach this using Limit Laws and rearranging the equation only?
What I know so far is that the numerator and denominator equal 0 if I take the limit now, so I need to somehow rearrange this.
Thanks.