# How do use the first derivative test to determine the local extrema #f(x) = xsqrt(25-x^2)#?

##### 1 Answer

Oct 14, 2015

#### Answer:

The extrema of your functions are

#### Explanation:

You compute the first derivative and find its roots. The derivative is computed as follows:

Since

This function equals zero if and only if its numerator equals zero, so

These are the local extrema of your function.