Precalculus Examples

$f (x) = \cos (2 x)$

Step 1

Find $f (- x)$ .

Tap for more steps...

Step 1.1

Find $f (- x)$ by substituting $- x$ for all occurrence of $x$ in $f (x)$ .

$f (- x) = \cos (2 (- x))$

Step 1.2

Multiply $- 1$ by $2$ .

$f (- x) = \cos (- 2 x)$

Step 2

A function is even if $f (- x) = f (x)$ .

Tap for more steps...

Step 2.1

Check if $f (- x) = f (x)$ .

Step 2.2

Since $\cos (- 2 x) = \cos (2 x)$ , the function is even.

The function is even

Step 3