local max. value is 68 at x = 1 and local min. values are−1647 at x = −6 and −316 at x = 5
F’(x) = 4x3 - 124x+120 = 0
⇒ 4(x3 - 31x+30) = 0
For x = 1, the given eq is 0
x -1 is a factor,
4(x -1)(x+6)(x -5) = 0
⇒ X = 1, -6,5
F’’(1))<0, 1 is the point of max.
F’’(-6) and f ’’(5) 0, -6 and 5 are point of min.
F(1) = 68
F(-6) = -1647
F(5) = -316