(a) Differentiate (x^2 + 1)^4

Question

(b) Hence find a primitive of 8x(x^2 + 1)^3 .

Answer 1

chain rule:

(a) 4(x^2+1)^3 * 2x
(b) not sure what you mean by "primitive"
The extrema (max and min) can be found where

8x(x^2+1)^3 = 0