Write the vertex of the function f(x) = -4x^2 - 12x + 9.
Find the vertex: f(x) = -4x2 - 12x + 9
Subtract 9 from both sides: f(x) - 9 = -4x2 - 12x
Factor out the -4: f(x) - 9 = -4(x2 + 3x)
Complete the square: f(x) - 9 - 9 = -4(x2 + 3x + 9/4)
f(x) - 18 = -4(x + 3/2)2
Vertex: (-3/2, 18)
