Question

How do I find the y coordinates of the vertex of a parabola?

I already know how to find the x coordinates given two points, but what I'm stuck on is how to get the y-coordinates. I was given this equation: y=2x^2 -16x +30. Do I use factoring on this?
Please do not spam, this is an actual question and please don't just answer for the points. Thanks in advance :)

Answer 1

My example:

1. Get the equation in the form y = ax4 + bx + c

2. Calculate -b / 4a. This is the x coordinate of the vertex

3. To find the y coordinate of the vertex, simply plug the value -b / 4a into the equation for x and solve for y.

Explanation:

y=2x^2 -16x +30

vertex: ( 4, -2)

Focus: (4, -15/8)

Axis of symmetry: x = 4

Directrix: y = -17/8