SOLUTION: I am trying to help my daughter. she was learning ax(squared) + bx + c = y, which she understands. However she was given vertex (2, -3) contains points (-1,-12) y-k=a(x-h)

Question 254282: I am trying to help my daughter.
she was learning ax(squared) + bx + c = y, which she understands.
However she was given
vertex (2, -3)
contains points (-1,-12)
y-k=a(x-h)squared
she has to find "a"
then plug in to the vertix form to find the ax form
Found 2 solutions by nerdybill, richwmiller:
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
given
vertex (2, -3)
contains points (-1,-12)
y-k=a(x-h)squared
she has to find "a"
then plug in to the vertex form to find the ax form
.
The "vertex form" of a parabola is:
y= a(x-h)^2+k
http://www.mathwarehouse.com/geometry/parabola/standard-and-vertex-form.php
.
y-k = a(x-h)^2
where
(h,k) is the vertex
.
Plug in what the problem gave:
vertex (2, -3)
contains points (-1,-12)
y-k = a(x-h)^2
Plugging in (2, -3) we get:
y-(-3) = a(x-2)^2
Plugging in our point (-1,-12)
-12-(-3) = a(-1-2)^2
-12+3 = a(-3)^2
-9 = a(9)
-1 = a
Answer by richwmiller(17219) (Show Source): You can put this solution on YOUR website!
(h,k) are the vertex coordinates
So plug those in
(2, -3) for (h,k)
(-1,-12) for (x,y)
y-k=a(x-h)^2
-12-(-3)=a(-1-2)^2
Mind your signs
-12+3=a(-3)^2
remember (-3)^2=+9
-9=a+(9)
-1=a

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