Originally Posted by
Plato This should be a lesson to you. Had you posted the basic question first, you would have had this reply sooner. That reduces to
$\displaystyle e^{-z}-e^{z}=-2e^{-z}-2e^{z}$
$\displaystyle 1-e^{2z}=-2-2e^{2z}$
$\displaystyle 3+e^{2z}=0$.
Can you solve that?