Answer:
y = 1/3 x 2 +4 x + 15
Step-by-step explanation:
y = a (x - h)2 + k
where (h,k) are the coordinates of the vertex and a is a multiplier
here (h,k) = ( - 6, 3)
y = a ( x + 6)2 + 3
to find a substitute (12,9) into the equation
9 = 18 a + 3
18 a = 9 - 3 = 6 a = 6/18 = 1/3
y = 1/3 (x + 6)2 + 3
distributing gives
y = 1/3 (x2 + 12x + 36) + 3
y = 1/3x2 + 4x + 15
