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

##### 1 Answer

Sep 15, 2015

#### Answer:

This function has no local extreme points because its derivative is never zero.

#### Explanation:

If

In fact,

Here's the graph of

graph{x-2tan(x) [-20, 20, -10, 10]}