Question

If f(x)=4-coshx/3+coshx,
f'(x)=?

Answer 1

If you mean f(x)= (4-coshx)/(3+coshx),
Let u = 4 - coshx and v = 3 + coshx
u' = -sinhx v' = sinhx
f'(x) = (v u'- u v')/(v^2)
Finish it by substution

Answer 2

Got it. Thanks!