Calculate d/dx (x 2 + 1) for the following choices of (u): (a) (u) = sin u

Calculate d/dx ƒ(x² + 1) for the following choices of ƒ(u):

(a) ƒ(u) = sin u 

(b) ƒ(u) = 3u^3/2 

(c) ƒ(u) = u² − u