Precalculus: Mathematics for Calculus, 7th Edition

$\dfrac{\dfrac{1}{\sqrt{x+h}}-\dfrac{1}{\sqrt{x}}}{h}=\dfrac{\sqrt{x}-\sqrt{x+h}}{h\sqrt{x^{2}+xh}}$
$\dfrac{\dfrac{1}{\sqrt{x+h}}-\dfrac{1}{\sqrt{x}}}{h}$ Evaluate the subtraction in the numerator: $\dfrac{\dfrac{1}{\sqrt{x+h}}-\dfrac{1}{\sqrt{x}}}{h}=\dfrac{\dfrac{\sqrt{x}-\sqrt{x+h}}{(\sqrt{x})(\sqrt{x+h})}}{h}=...$ Evaluate the division: $...=\dfrac{\sqrt{x}-\sqrt{x+h}}{h(\sqrt{x})(\sqrt{x+h})}=...$ Evaluate the product in the denominator: $...=\dfrac{\sqrt{x}-\sqrt{x+h}}{h\sqrt{x^{2}+xh}}$