Parabola by vertex and a point

Problem:



Solution:

First of all, the parabola open downwards, the leading coefficient is negative.

The maximum y value is 4, that's why the last box should be 4. (The maximum of the negative of a square value is 0)

The maximum value attained when x = -5, that's why the middle box should be 5.

Last but not least, when x = -1, y = 0, the means k(-1 + 5)^2 + 4 = 0, that means the first box is -1/4

Therefore the equation is $-\frac{1}{4}(x + 5)^2 + 4$