Quotient Rule

A formula for the derivative of the quotient of a pair of functions
\[ \frac{\mathrm{d}\left(\frac{f}{g}\right)}{\mathrm{d}x} = \frac{\frac{\mathrm{d}f}{\mathrm{d}x} \times g - f \times \frac{\mathrm{d}g}{\mathrm{d}x}}{g^2} \]