how do i do this

Question

A parabola opening up or down has vertex 

(

0

,

0

)

 and passes through 

(

–

2

,

1

)

.

 Write its equation in vertex form.



Answer 1

A parabola with vertex (h, k) has the general formula y = a(x-h)² + k

Your vertex is given to be at h = 0, k = 0, so the formula simplifies to y = ax²

To find the value of a, plug in the given point (x, y) = (-2, 1) and solve for a.

Answer 2

y = a(x-h)^2 + k is the vertex form of a parabola with vertex (h,k).

Plug in (0,0) for (h,k).

y = a(x-0)^2 + 0 = ax^2

Find a by plugging in the point (-2,1) for (x,y)

1 = a*(-2)^2 = 4a

1/4 = a

y = (1/4)x^2