(Note: in this answer I will use the notation y' to represent the differential of y, and by the same reasoning y'' denotes the differential of y', or the second derivative of y.)
First write cosh and sinh as exponentials, from their respective definitions:sinh x = 1/2 (ex - e-x)cosh x = 1/2 (ex + e-x)So: 3 * 1/2 (ex + e