Question

Hey can someone show me how to prove that cosh3x = 4cosh^3x - 3coshx plz...

Answer 1

Please, try to use these identities:
\[\cosh(x+y)=\cosh x \cosh y+\sinh x \sinh y\]
and:
\[\sinh(x+y)=\sinh x \cosh y+\cosh x \sinh y\]
hint:
\[\cosh(3x)=\cosh(2x+x)=...\]

Answer 2

thank you but am suppose to solve it using exponents...:(