Given that the image of quadratic function passes through (- 1,0), (5,0), the maximum value of function is 6, find the analytic expression of function How to solve this problem with undetermined coefficient method?

Given that the image of quadratic function passes through (- 1,0), (5,0), the maximum value of function is 6, find the analytic expression of function How to solve this problem with undetermined coefficient method?

The point given in this paper is special, which is the intersection of function image and X axis. Therefore, the undetermined coefficient method adopts the intersection formula y = a (x-x1) (x-x2)
x1=-1,x2=5.
y=a(x+1)(x-5)
Because the vertex is on the axis of symmetry, and the axis of symmetry x = (x1 + x2) / 2 = 2
So substitute (2,6)
-9a=6,a=-2/3
So the expression is y = - 2 / 3 (x + 1) (X-5) = - 2x & # / 3 + 8x / 3 + 10 / 3