# What is the y-coordinate of the vertex of a parabola with the following equation #y = x^2 - 8x + 18#?

##### 1 Answer

Vertex = (4,2)

#### Explanation:

To find the vertex of a quadratic equation you can either use use the vertex formula or put the quadratic in vertex form:

**Method 1:** Vertex formula

a is the coefficient of the first term in the quadratic, b is the coefficient of the second term and c is the coefficient of the third term in the quadratic.

In this case a = 1 and b = -8, so substituting these values into the formula above gives:

which becomes:

which simplifies to:

**Method 2:** Vertex form

vertex form looks like this:

To convert from quadratic form to vertex form substitute the variables in the next equation with the coefficients of the quadratic

In this case b = -8 and c = 18

Substituting these variables we get

Which becomes:

which simplifies to:

This is called the vertex form because the vertex can be easily found in this form.

Note: This method can be quicker than the first method but only works when the coefficient of a is 1.