Determine if Odd, Even, or Neither f(x)=2x^3-18x

$f (x) = 2 x^{3} - 18 x$

Step 1

Find $f (- x)$ .

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

$f (- x) = 2 {(- x)}^{3} - 18 (- x)$

Simplify each term.

Apply the product rule to $- x$ .

$f (- x) = 2 ({(- 1)}^{3} x^{3}) - 18 (- x)$

Raise $- 1$ to the power of $3$ .

$f (- x) = 2 (- x^{3}) - 18 (- x)$

Multiply $- 1$ by $2$ .

$f (- x) = - 2 x^{3} - 18 (- x)$

Multiply $- 1$ by $- 18$ .

$f (- x) = - 2 x^{3} + 18 x$

Step 2

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

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

Since $- 2 x^{3} + 18 x$ $\neq$ $2 x^{3} - 18 x$ , the function is not even.

The function is not even

Step 3

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

Find $- f (x)$ .

Multiply $2 x^{3} - 18 x$ by $- 1$ .

$- f (x) = - (2 x^{3} - 18 x)$

Apply the distributive property.

$- f (x) = - (2 x^{3}) - (- 18 x)$

Multiply.

Multiply $2$ by $- 1$ .

$- f (x) = - 2 x^{3} - (- 18 x)$

Multiply $- 18$ by $- 1$ .

$- f (x) = - 2 x^{3} + 18 x$

Since $- 2 x^{3} + 18 x = - 2 x^{3} + 18 x$ , the function is odd.

The function is odd

Step 4