f(x) = x^3
a = 0, b = 1, c = 2とすると、h(x) = 3x^2 - 2x

f'(x) = 3x^2
h'(x) = 6x - 2

f''(x) = 6x
h''(x) = 6

f''(x) = h''(x)となるのは、x = 1
f'(1) = 3, h'(1) = 4なので、成り立たない