Precalculus Examples

$h (x) = \frac{9 x}{x (x^{2} - 36)}$

Step 1

Set the denominator in $\frac{9 x}{x (x^{2} - 36)}$ equal to $0$ to find where the expression is undefined.

$x (x^{2} - 36) = 0$

Step 2

Solve for $x$ .

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Step 2.1

If any individual factor on the left side of the equation is equal to $0$ , the entire expression will be equal to $0$ .

$x = 0$

$x^{2} - 36 = 0$

Step 2.2

Set $x$ equal to $0$ .

$x = 0$

Step 2.3

Set $x^{2} - 36$ equal to $0$ and solve for $x$ .

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Step 2.3.1

Set $x^{2} - 36$ equal to $0$ .

$x^{2} - 36 = 0$

Step 2.3.2

Solve $x^{2} - 36 = 0$ for $x$ .

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Step 2.3.2.1

Add $36$ to both sides of the equation.

$x^{2} = 36$

Step 2.3.2.2

Take the specified root of both sides of the equation to eliminate the exponent on the left side.

$x = \pm \sqrt{36}$

Step 2.3.2.3

Simplify $\pm \sqrt{36}$ .

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Step 2.3.2.3.1

Rewrite $36$ as $6^{2}$ .

$x = \pm \sqrt{6^{2}}$

Step 2.3.2.3.2

Pull terms out from under the radical, assuming positive real numbers.

$x = \pm 6$

Step 2.3.2.4

The complete solution is the result of both the positive and negative portions of the solution.

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Step 2.3.2.4.1

First, use the positive value of the $\pm$ to find the first solution.

$x = 6$

Step 2.3.2.4.2

Next, use the negative value of the $\pm$ to find the second solution.

$x = - 6$

Step 2.3.2.4.3

The complete solution is the result of both the positive and negative portions of the solution.

$x = 6, - 6$

Step 2.4

The final solution is all the values that make $x (x^{2} - 36) = 0$ true.

$x = 0, 6, - 6$

Step 3

The domain is all values of $x$ that make the expression defined.

Interval Notation:

$(- \infty, - 6) \cup (- 6, 0) \cup (0, 6) \cup (6, \infty)$

Set-Builder Notation:

${x | x \neq 0, 6, - 6}$

Step 4