Question

find vertex of parabola f(x)= 5-(x+20) squared. [ the (x+20) is squared. I don't know how to write that]

Answer 1

The vertex of a parabola in the form y = a(x - h)^2 + k is the point with coordinates (h , k)
The parabola f(x)=5 - (x + 20)^2 can be written in the above format as:

y = -(x + 20)^2 + 5 Or y = -1(x - -20)^2 + 5.
In this format you can see the values of the coefficients a=-1, h=-20, k=5.

So the vertex is the point with coordinates ( -20, 5)