The minimum values of the three functions are:1; Under the root sign1+t; 1-t under the root sign

Then the unary cubic equation can be expressed as: (x-1) (1+t under the root number x) (1-t under the root number x) = 0.

Comparing the coefficient with the formula x3+a x2+bx+c=0, we can draw the conclusion that a=f(t) and b=g(t) can be substituted into the calculation.

(2)(3) For a problem, first substitute two points into the equation and do subtraction to get the formula (*).

Then the derivative of f(x)=x3+a x2+bx+c is obtained.

The two points f~(x)=3x2+2ax+b=0 are the abscissa of the extreme point. According to Vieta theorem

Get a and b expressions of x 1+x2, x 1*x2, and substitute them into formula (*) to get m-n.