Express cosh(4x) in terms of powers of cosh(x) and/or sinh(x)

[ryley]

Hey guys, my girlfriend does calculus 2 and she asked me a question from her notes; "Express cosh(4x) in terms of powers of cosh(x) and/or sinh(x)". It was simple enough to do using the cosh double angle formula (which is what I have a feeling the solutions will do), but I wanted to have a go at it using something similar to the de Moivre/binomial method used in the analogous normal trig question. I ran into a few problems, so could someone please show me a better way of doing it other than double angle formula?

thanks,

ryley

[ryley]

sorry, nvm, i've got it now