How do you find the derivative of tan^4 (x)tan4(x)?
1 Answer
May 19, 2017
By using the power rule
d/(dx)[(u(x))^n] = n [u(x)]^(n-1)ddx[(u(x))n]=n[u(x)]n−1 , whereu(x)u(x) is a function ofxx ,
and the chain rule
d/(dx)[f(u)] = (df)/(du)(du)/(dx)ddx[f(u)]=dfdududx , wheref = f(u(x))f=f(u(x)) .
If we rewrite
f(u) = u^4f(u)=u4 u(x) = tanxu(x)=tanx
As a result:
color(blue)(d/(dx)[f(u)]) = (df)/(du)(du)/(dx)ddx[f(u)]=dfdududx
d/(du)[u^4]cdot d/(dx)[tanx]ddu[u4]⋅ddx[tanx]
= 4u^3 cdot sec^2x=4u3⋅sec2x
= color(blue)(4tan^3xsec^2x)=4tan3xsec2x