This one is simple. Distribute the negative (-) to the 1/x. The 1/x becomes negative and you can cancel the 1/x out. This leaves you with "h". Hope this helps!
[tex]\frac{1}{x+h}-\frac{1}{x}[/tex] You need a common denominator. That will be x(x +h). [tex]\frac{x}{x(x+h)}-\frac{(x+h)}{x(x+h)} \\ \\ \frac{x-(x+h)}{x(x+h)} \\ \\ \frac{-h}{x^2+hx}[/tex]
