Question

Image: The parabola passes through 2, 20 and 3, 15 then continues to its vertex at the plotted and labeled point 4, 8. It continues through 5, 10 and 7, 20. All values are approximate.

What is the vertex form of the graphed equation?

y = 2 (x + 4)^2 + 8
y = 2 (x - 4)^2 + 8
y = 2 (x - 4)^2 - 8
y = -2 (x - 4)^2 + 8

Answer 1

Vertex at (4,8) → form y = a(x − 4)^2 + 8. Use (5,10): 10 = a(5−4)^2 + 8 → 10 = a + 8 → a = 2.

So y = 2(x − 4)^2 + 8.