The image of a quadratic function passes through three points ABC, the coordinate of point a is (- 1,0), the coordinate of point B is (4,0), and point C is on the positive half axis of Y axis And ab = OC (1) Find the coordinates of point C; (2) Find the analytic expression of the quadratic function and write out its axis of symmetry;

The image of a quadratic function passes through three points ABC, the coordinate of point a is (- 1,0), the coordinate of point B is (4,0), and point C is on the positive half axis of Y axis And ab = OC (1) Find the coordinates of point C; (2) Find the analytic expression of the quadratic function and write out its axis of symmetry;

1) Let y = a (x + 1) (x-4) x = 0, we can get y = - 4A, that is, point C coordinate is (0, - 4A) AB = 4 + 1 = 5oC = - 4A, so - 4A = 5, point a = - 5 / 4C coordinate is (0,5) 2) y = - 5 / 4 (x + 1) (x-4) = - 5 / 4 (x ^ 2-3x-4) = - (5 / 4) x ^ 2 + (15 / 4) x + 5, axis of symmetry is x = (4-1) / 2 = 3 / 2