Solution, first take the derivative of fx and get f'x=3x square +2ax+b because 1 and-1 are extreme points.

So f( 1)=f(- 1)=0 gives a = 0 and b =-3, so f'x=3x -3=3(x-1) fx=x cube -3x.

So hx=9(3x6 power -9x4 power-10x square+4)-c.

Take the derivative of hx and get h'x= 18x5 -36x3 -20x).

Let it =0 and x= have three values.

However, =0 is not necessarily an extreme point, which needs to be verified one by one, that is, the left side and the other side of the extreme point cannot be greater than 0 or less than 0 at the same time in the derivative function ... If you don't understand, please ask.

Hungry. Maybe there is a mistake in the writing, but the idea is probably like this. The third year of high school passed quickly.