# How do you differentiate 1/sqrt(1-x^2)?

$- \frac{x}{\sqrt{{\left(1 - {x}^{2}\right)}^{3}}}$
$\frac{d}{\mathrm{dx}} {\left(1 - {x}^{2}\right)}^{- \frac{1}{2}} = - \frac{1}{2} {\left(1 - {x}^{2}\right)}^{- \frac{3}{2}} \cdot 2 x$