Winter vacation homework, a senior three math student, knows that the image intersection point of quadratic function y=f(x) is at two points, A and B (see description for details).
(1) Let the quadratic function be f (x) = ax? 0? 5+bx+c, ∫ It intersects the Y axis at (∴,c=4), ∴, c=4. Let the abscissa of the intersection of point A and point B with vx axis be x 1 and x2 respectively, then when the distance between AB = √, f(x) > or =a is constant, it is just f (.