Question

Given the standard form, how do you find the y co-ordinate of the vertex of a quadratic function?

Answer 1

What's really nice about the vertex of a quadratic equation is that it's pretty easy to find. To do so, we use the following steps:

1. Get the equation in the form y = ax2 + bx + c.
2. Calculate -b / 2a. This is the x-coordinate of the vertex.
3. To find the y-coordinate of the vertex, simply plug the value of -b / 2a into the equation for x and solve for y. This is the y-coordinate of the vertex.

After following these steps, you have your x and y coordinates of the vertex, so you have your vertex. Not too bad, huh? We see that the vertex of a quadratic equation, y = ax2 + bx + c, is the following point.

(-b / 2a, a(-b / 2a)^2 + b(-b / 2a) + c)