Quadratics stretching and vertex form help?

[federox]

Hi, so the questions tells me to...
Evaluate the following function at 3,-3,0, and z
D(r)= -(r-2)^2+8
I got the correct answers for the first three numbers but got "z" incorrect. Can someone please show me how to get the correct answer?

This is what I did...
D(z)= -(z-2)^2+8
= -z^2+4+8
= -z^2+12

[curlz]

-(r-2)^2+8=
-[r^2-4r+4]+8=
-r^2+4r+4