Finding the function of a parabola with vertex point and additional point?

Find the function of a parabola if it passes through (0,0) and the vertex is (-2,4). Put into vertex form, intercept and standard.

?2016-12-08T23:49:04Z

Favorite Answer

y-4 = a(x+2)^2
-4 = 4a
a = -1
i) y = -(x+2)^2 + 4
ii) y = -[x^2+4x+4] + 4
y = -x^2-4x

Randy P2016-12-08T23:38:38Z

Vertex form with vertex (h, k): y = a(x - h)^2 + k
"the vertex is (-2,4)"
y = a(x + 2)^2 + 4

"it passes through (0,0)"
0 = a(0 + 2)^2 + 4
Solve for a and you've got the complete function.