a)
f'(x) = 3x^2
f''(x) = 6x
f''(x) = 0
6x = 0 => x = 0 punct de inflexiune
f(0) = -1
b)
f'(x) = 4x^3 - 12x^2
f''(x) = 12x^2 - 24x
f''(x) = 0
12x^2 - 24x = 0, impartim prin 12
x^2 - 2x = 0
x(x-2) = 0
x1 = 0 , x2 = 2 puncte de inflexiune
f(0) = 0
f(2) = -16
