Please help with math question below:

Question

Express the triple angle formula of tangent (i.e. tan〖(3x)〗) in terms of tanx.

Answer 1

easy to look up, here is one such page
http://www.trans4mind.com/personal_development/mathematics/trigonometry/multipleAnglesTangent.htm

If you have to actually develop it,
use
tan(A+B) = (tanA + tanB)/(1 - tanAtanB)
on tan(3x) = tan(2x+1)
after doing tan2x first.