Trigonometry Examples

$\frac{9}{x - 4} - \frac{9}{x} = \frac{36}{x^{2} - 4 x}$

Step 1

Factor $x$ out of $x^{2} - 4 x$ .

Tap for more steps...

Step 1.1

Factor $x$ out of $x^{2}$ .

$\frac{9}{x - 4} - \frac{9}{x} = \frac{36}{x \cdot x - 4 x}$

Step 1.2

Factor $x$ out of $- 4 x$ .

$\frac{9}{x - 4} - \frac{9}{x} = \frac{36}{x \cdot x + x \cdot - 4}$

Step 1.3

Factor $x$ out of $x \cdot x + x \cdot - 4$ .

$\frac{9}{x - 4} - \frac{9}{x} = \frac{36}{x (x - 4)}$

Step 2

Find the LCD of the terms in the equation.

Tap for more steps...

Step 2.1

Finding the LCD of a list of values is the same as finding the LCM of the denominators of those values.

$x - 4, x, x (x - 4)$

Step 2.2

Since $x - 4, x, x (x - 4)$ contains both numbers and variables, there are four steps to find the LCM. Find LCM for the numeric, variable, and compound variable parts. Then, multiply them all together.

Steps to find the LCM for $x - 4, x, x (x - 4)$ are:

1. Find the LCM for the numeric part $1, 1, 1$ .

2. Find the LCM for the variable part $x^{1}, x^{1}$ .

3. Find the LCM for the compound variable part $x - 4, x - 4$ .

4. Multiply each LCM together.

Step 2.3

The LCM is the smallest positive number that all of the numbers divide into evenly.

1. List the prime factors of each number.

2. Multiply each factor the greatest number of times it occurs in either number.

Step 2.4

The number $1$ is not a prime number because it only has one positive factor, which is itself.

Not prime

Step 2.5

The LCM of $1, 1, 1$ is the result of multiplying all prime factors the greatest number of times they occur in either number.

$1$

Step 2.6

The factor for $x^{1}$ is $x$ itself.

$x^{1} = x$

$x$ occurs $1$ time.

Step 2.7

The LCM of $x^{1}, x^{1}$ is the result of multiplying all prime factors the greatest number of times they occur in either term.

$x$

Step 2.8

The factor for $x - 4$ is $x - 4$ itself.

$(x - 4) = x - 4$

$(x - 4)$ occurs $1$ time.

Step 2.9

The LCM of $x - 4, x - 4$ is the result of multiplying all factors the greatest number of times they occur in either term.

$x - 4$

Step 2.10

The Least Common Multiple $LCM$ of some numbers is the smallest number that the numbers are factors of.

$x (x - 4)$

Step 3

Multiply each term in $\frac{9}{x - 4} - \frac{9}{x} = \frac{36}{x (x - 4)}$ by $x (x - 4)$ to eliminate the fractions.

Tap for more steps...

Step 3.1

Multiply each term in $\frac{9}{x - 4} - \frac{9}{x} = \frac{36}{x (x - 4)}$ by $x (x - 4)$ .

$\frac{9}{x - 4} (x (x - 4)) - \frac{9}{x} (x (x - 4)) = \frac{36}{x (x - 4)} (x (x - 4))$

Step 3.2

Simplify the left side.

Tap for more steps...

Step 3.2.1

Simplify each term.

Tap for more steps...

Step 3.2.1.1

Cancel the common factor of $x - 4$ .

Tap for more steps...

Step 3.2.1.1.1

Factor $x - 4$ out of $x (x - 4)$ .

$\frac{9}{x - 4} ((x - 4) x) - \frac{9}{x} (x (x - 4)) = \frac{36}{x (x - 4)} (x (x - 4))$

Step 3.2.1.1.2

Cancel the common factor.

$\frac{9}{x - 4} ((x - 4) x) - \frac{9}{x} (x (x - 4)) = \frac{36}{x (x - 4)} (x (x - 4))$

Step 3.2.1.1.3

Rewrite the expression.

$9 x - \frac{9}{x} (x (x - 4)) = \frac{36}{x (x - 4)} (x (x - 4))$

Step 3.2.1.2

Cancel the common factor of $x$ .

Tap for more steps...

Step 3.2.1.2.1

Move the leading negative in $- \frac{9}{x}$ into the numerator.

$9 x + \frac{- 9}{x} (x (x - 4)) = \frac{36}{x (x - 4)} (x (x - 4))$

Step 3.2.1.2.2

Cancel the common factor.

$9 x + \frac{- 9}{x} (x (x - 4)) = \frac{36}{x (x - 4)} (x (x - 4))$

Step 3.2.1.2.3

Rewrite the expression.

$9 x - 9 (x - 4) = \frac{36}{x (x - 4)} (x (x - 4))$

Step 3.2.1.3

Apply the distributive property.

$9 x - 9 x - 9 \cdot - 4 = \frac{36}{x (x - 4)} (x (x - 4))$

Step 3.2.1.4

Multiply $- 9$ by $- 4$ .

$9 x - 9 x + 36 = \frac{36}{x (x - 4)} (x (x - 4))$

Step 3.2.2

Simplify by adding terms.

Tap for more steps...

Step 3.2.2.1

Subtract $9 x$ from $9 x$ .

$0 + 36 = \frac{36}{x (x - 4)} (x (x - 4))$

Step 3.2.2.2

Add $0$ and $36$ .

$36 = \frac{36}{x (x - 4)} (x (x - 4))$

Step 3.3

Simplify the right side.

Tap for more steps...

Step 3.3.1

Cancel the common factor of $x (x - 4)$ .

Tap for more steps...

Step 3.3.1.1

Cancel the common factor.

$36 = \frac{36}{x (x - 4)} (x (x - 4))$

Step 3.3.1.2

Rewrite the expression.

$36 = 36$

Step 4

Since $36 = 36$ , the equation will always be true for any value of $x$ .

All real numbers

Step 5

The result can be shown in multiple forms.

All real numbers

Interval Notation:

$(- \infty, \infty)$