f.4 mathz,,, functions and graphs.

I is given that (-5,0) and (0,5) are two points on the graph of the quadratic function y=f(x)=a+bx-x^2.

a) Find the values of a and b.

b) Find the maximum value of y.

c) After translating the graphh of y=f(x) 4 untis to the left, it becomes the graph of y=g(x). Express g(x) in terms of x.