Determine if Odd, Even, or Neither f(x)=x^4-9x^2

$f (x) = x^{4} - 9 x^{2}$

Step 1

Find $f (- x)$ .

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

$f (- x) = {(- x)}^{4} - 9 {(- x)}^{2}$

Simplify each term.

Apply the product rule to $- x$ .

$f (- x) = {(- 1)}^{4} x^{4} - 9 {(- x)}^{2}$

Raise $- 1$ to the power of $4$ .

$f (- x) = 1 x^{4} - 9 {(- x)}^{2}$

Multiply $x^{4}$ by $1$ .

$f (- x) = x^{4} - 9 {(- x)}^{2}$

Apply the product rule to $- x$ .

$f (- x) = x^{4} - 9 ({(- 1)}^{2} x^{2})$

Raise $- 1$ to the power of $2$ .

$f (- x) = x^{4} - 9 (1 x^{2})$

Multiply $x^{2}$ by $1$ .

$f (- x) = x^{4} - 9 x^{2}$

Step 2

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

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

$x^{4} - 9 x^{2} = x^{4} - 9 x^{2}$

Since $x^{4} - 9 x^{2} = x^{4} - 9 x^{2}$ , the function is even.

The function is even

Step 3