I have the expression
ss =
As μ
(2 I k η1 Sinh[y η1] -
(I k (2 k^2 - k2^2) Cosh[H η1] Sinh[y η2])/(η2 Cosh[H η2]) +
(I k2^2 (2 k^2 - k2^2) Cosh[H η1] Sinh[y η2])/(2 k η2 Cosh[H η2]));
I want to simplify it using the relation
-4 k^2 η1 η2 Cosh[H η2] Sinh[H η1] + (-2 k^2 + k2^2)^2 Cosh[H η1] Sinh[H η2] == 0
The answer is:
However, I couldn't do get that using Mathematica.