Question

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

What is the vertex form of the graphed equation?

(1 point)

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) ⇒ y = a(x − 4)^2 + 8. Use (5,10): 10 = a(1)^2 + 8 ⇒ a = 2.

So y = 2(x − 4)^2 + 8.