The graph of which function will have a maximum and a y-intercept if 4?

-x^2+2x+4

It will be a parabola withe line of symmetry = y axis and will open downwards. The coefficient of x^2 will be - 1.

As it will have a maximum and y intercept of y = 4 the function will be

f (x) = - x^2 + 4