Question

The vertex of the parabola below is at the point (-2, -1), and the point (-1, 1) is on the parabola. Write the equation of the parabola.

Answer 1

y = 2(x +2)^2 -1

Explanation:

The vertex form of the equation of a parabola is ...

y = a(x -h)^2 +k . . . . . vertex (h, k), scale factor "a"

We know the vertex, so we can find the scale factor from the other point.

1 = a(-1+2)^2 -1 = a -1

2 = a . . . . . . add 1

The equation of the parabola is ...

y = 2(x +2)^2 -1