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