$$\displaystyle\frac{d}{d x } \left( { \left( { e }^{ x } - { e }^{ -x } \right) }^{ -1 } \right)$$
$\frac{-e^{x}-e^{3x}}{\left(e^{2x}-1\right)^{2}}$
$\frac{e^{x}\left(e^{2x}-1\right)^{3}+8e^{5x}-8e^{3x}}{\left(e^{2x}-1\right)^{4}}$
