Question

integrate 6cos^3(3x)

Answer 1

hello :)
have you attempted this integral ?

Answer 2

there are several ways to solve this integral,
one of the ways include, writing \(\cos^3 3x \) as \(\cos^2 x \times \cos x\)
and do a 'u' substitution u= sin x

Answer 3

will you try this method ? if you get stuck, ask me, i'll help you out :)