Answer:
(9, 20)
Step-by-step explanation:
2 ways to do this:
1) use a graphing calculator and find the vertex off the graph. Vertex is: (9, 20)
2) use the formula x=-b/2a, then substitute the found value of x to find y.
a=-1/3, b = 6, c=-7
x=-6/(2(-1/3)) = -6/(-2/3) = (-6)(2) / (-2) = 9
f(9) = -1/3(9)² + 6(9) - 7 = -27 + 54 - 7 = 20
Vertex is: (9,20)
