Precalculus Examples

$Y = x^{2} + 3 x + 9$

Step 1

Write $Y = x^{2} + 3 x + 9$ as a function.

$f (x) = x^{2} + 3 x + 9$

Step 2

Find $f (- x)$ .

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Step 2.1

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

$f (- x) = {(- x)}^{2} + 3 (- x) + 9$

Step 2.2

Simplify each term.

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Step 2.2.1

Apply the product rule to $- x$ .

$f (- x) = {(- 1)}^{2} x^{2} + 3 (- x) + 9$

Step 2.2.2

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

$f (- x) = 1 x^{2} + 3 (- x) + 9$

Step 2.2.3

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

$f (- x) = x^{2} + 3 (- x) + 9$

Step 2.2.4

Multiply $- 1$ by $3$ .

$f (- x) = x^{2} - 3 x + 9$

Step 3

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

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Step 3.1

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

Step 3.2

Since $x^{2} - 3 x + 9$ $\neq$ $x^{2} + 3 x + 9$ , the function is not even.

The function is not even

Step 4

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

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Step 4.1

Find $- f (x)$ .

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Step 4.1.1

Multiply $x^{2} + 3 x + 9$ by $- 1$ .

$- f (x) = - (x^{2} + 3 x + 9)$

Step 4.1.2

Apply the distributive property.

$- f (x) = - x^{2} - (3 x) - 1 \cdot 9$

Step 4.1.3

Simplify.

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Step 4.1.3.1

Multiply $3$ by $- 1$ .

$- f (x) = - x^{2} - 3 x - 1 \cdot 9$

Step 4.1.3.2

Multiply $- 1$ by $9$ .

$- f (x) = - x^{2} - 3 x - 9$

Step 4.2

Since $x^{2} - 3 x + 9$ $\neq$ $- x^{2} - 3 x - 9$ , the function is not odd.

The function is not odd

Step 5

The function is neither odd nor even

Step 6