Answer
$\frac{-1}{(x+h)x}$
Work Step by Step
$\dfrac{\frac{1}{x+h}-\frac{1}{x}}{h}=\dfrac{\frac{x}{(x+h)x}-\frac{x+h}{x(x+h)}}{h}=\dfrac{\frac{x-(x+h)}{(x+h)x}}{h}=\frac{x-x-h}{h(x+h)x}=\frac{-h}{h(x+h)x}=\frac{-1}{(x+h)x}$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.