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

1 Answer
May 30, 2015

Quadrati equation y = ax^2 + bx + c y=ax2+bx+c.

c = 12, find a and b.

x of vertex: (-b/2a) = -2 -> b = 4a (b2a)=2b=4a

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

-> a = 6/4 = 3/2a=64=32

Equation y = 3/2(x^2) + 6x + 12y=32(x2)+6x+12

Check:

x of vertex: (-b/(2a)) = -6/3 = -2(b2a)=63=2 OK
f(-2) = (3/2)4 - 12 + 12 = 6f(2)=(32)412+12=6 OK