Question 626771
determine the quadratic function f whose graph is given
a. vertex is (3,-12)
b. y-intercept is -3
in the from f(x)= ax^2+bx+c
.
y-intercept is -3
this means the (x,y) coordinate is (0,-3)
.
Vertex form of quadratic:
y = a(x-h)^2 + k 
plug in data:
-3 = a(0-3)^2 + (-12) 
-3 = a(-3)^2 - 12
-3 = a(9) - 12
9 = 9a
1 = a
.
our quadratic:
y = (x-3)^2 - 12
y = (x-3)(x-3) - 12
y = x^2-6x+9 - 12
y = x^2-6x-3 (this is what they're looking for)