How do you write the quadratic in vertex form given vertex is (-2,6) and y intercpet is 12 ?

Question

1281 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-05-30T22:22:46

Quadrati equation #y = ax^2 + bx + c #.

c = 12, find a and b.

x of vertex: #(-b/2a) = -2 -> b = 4a #

y of vertex: #f(-2) = 6 = 4a - 2b + 12 --> 4a - 8a + 12 = 6 ->

-> # a = 6/4 = 3/2#

Equation #y = 3/2(x^2) + 6x + 12#

Check:

x of vertex: #(-b/(2a)) = -6/3 = -2# OK
#f(-2) = (3/2)4 - 12 + 12 = 6# OK