# What is the vertex of #y= -8x^2 − 6x + 128#?

##### 1 Answer

#### Explanation:

There are actually 2 methods of going about this.

Method A is completing the square.

To do this, the function needs to be in the form

First, separate the constant from the first two terms:

Then factor out -8:

Next, divide the

Make sure to SUBTRACT

Simplify to get:

Method 2: Calculus

There is a method that is sometimes easier or harder. It involves taking the derivative of the equation, setting it equal to 0, and substituting that solution back into the original equation.

**If you don't understand, don't worry. This method is harder for this specific question.

Substitute this back into the original equation to get 129.125, so the vertex is