The vertex we want must be in the form of the point (-b/2a, y).
1. Find x.
x = -b/2a
x = -4/2(-2)
x = -4/(-4)
x = 1
2. Replace every x in the given function with 1 to find y.
y = -2(1)^2 + 4(1) + 1
y = -2 + 4 + 1
y = -2 + 5
y = 3
Our vertex is the point (1, 3).
Understand?
