# How do you find the vertex of #F(x)=x^2+2x-8#?

##### 3 Answers

-1

#### Explanation:

For a quadratic function like this, the vertices are points of symmetry.

We can use a shortcut such that:

In your case,

Confirm it on a graph.

graph{x^2+2x-8 [-25.8, 25.8, -18.1, 7.7]}

The vertex is when the gradient is 0.

#### Explanation:

Differentiate and find

Therefore the vertex is:

Vertex is (-1, -9)

#### Explanation:

To find the x-value of the vertex, we use the formula

By substituting we get

Once you find x, substitute back into the equation to find y.

Putting the two numbers together you get the coordinates