20 14 what to do with the 23 questions in the mathematics volume of Henan senior high school entrance examination, the finale of the senior high school entrance examination. It is better to have some explanations about the topic, not just the process. This problem is the finale of quadratic function, and it is a comprehensive problem. This paper investigates the images and properties of quadratic function and linear function, coordinates of points, undetermined coefficient method, diamond, similar triangles and other knowledge points, focusing on the flexible application of classified discussion ideas and equation ideas. Note that this is to be discussed in the process of solving problems, and the answer/exercise/math /799565 is not very difficult, step by step.

As shown in the figure, parabola y=-x2+bx+c intersects with X axis at points A (- 1 0) and B (5 5,0), straight line y=-3x/4+3 intersects with Y axis at point C and X axis at point D, point P is a moving point on the parabola above X axis, and intersection point P is PF ⊥.

(1) Find the analytical formula of parabola;

(2) If PE=5EF, find the value of m;

(3) If the point E' is the symmetrical point of the point E with respect to the straight line PC, is there a point P that makes the point E' fall on the Y axis? If it exists, please directly write the coordinates of the corresponding point p; If it does not exist, please explain why.