Answer:
Vertex: (-3. -8)
Step-by-step explanation:
Quickest and easiest way to do this is to using a graphing calc and graph the function. Once you have done so, trace the graph to the lowest point of the graph. You should be able to see that (-3, -8) is your answer.
Alternatively, you can convert this function into f(x) = a(bx - h)² + k (by Completing the Square) form to find (-h, k) as your vertex.