9514 1404 393
Answer:
f(x) = -4x^2 +48x -129
Step-by-step explanation:
It usually works well to compute the square first. That is, simplify according to the order of operations.
f(x) = -4(x^2 -12x +36) +15
f(x) = -4x^2 +48x -144 +15
f(x) = -4x^2 +48x -129
You have the correct axis of symmetry value. Nice work.
Plug that x value into the equation to get...
y = -2x^2 - 12x - 10
y = -2*(-3)^2 - 12*(-3) - 10 <<-- replace every x with -3; then use PEMDAS
y = -2*(9) - 12*(-3) - 10
y = -18 + 36 - 10
y = 18 - 10
y = 8
The vertex is the ordered pair (-3, 8)
Note: the axis of symmetry is the vertical line through the vertex
