# How do you find the critical numbers for #y = x * sqrt( 9 - x^2)# to determine the maximum and minimum?

##### 1 Answer

There is a local minimum at

#### Explanation:

This equation is in factored form, so it is easy to list the

The

Also note that

Now let's take the derivative and find it's intercepts.

To find the roots of the derivative, set

This only happens when

When

When

This means that there is a local minimum at

When

This means that there is a local maximum at

graph{xsqrt(9-x^2) [-4, 4, -5, 5]}