Trigonometry Examples

$| x + 3 | - 9 = 2 x$

Step 1

Add $9$ to both sides of the equation.

$| x + 3 | = 2 x + 9$

Step 2

Remove the absolute value term. This creates a $\pm$ on the right side of the equation because $| x | = \pm x$ .

$x + 3 = \pm (2 x + 9)$

Step 3

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

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Step 3.1

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

$x + 3 = 2 x + 9$

Step 3.2

Move all terms containing $x$ to the left side of the equation.

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Step 3.2.1

Subtract $2 x$ from both sides of the equation.

$x + 3 - 2 x = 9$

Step 3.2.2

Subtract $2 x$ from $x$ .

$- x + 3 = 9$

Step 3.3

Move all terms not containing $x$ to the right side of the equation.

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Step 3.3.1

Subtract $3$ from both sides of the equation.

$- x = 9 - 3$

Step 3.3.2

Subtract $3$ from $9$ .

$- x = 6$

Step 3.4

Divide each term in $- x = 6$ by $- 1$ and simplify.

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Step 3.4.1

Divide each term in $- x = 6$ by $- 1$ .

$\frac{- x}{- 1} = \frac{6}{- 1}$

Step 3.4.2

Simplify the left side.

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Step 3.4.2.1

Dividing two negative values results in a positive value.

$\frac{x}{1} = \frac{6}{- 1}$

Step 3.4.2.2

Divide $x$ by $1$ .

$x = \frac{6}{- 1}$

Step 3.4.3

Simplify the right side.

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Step 3.4.3.1

Divide $6$ by $- 1$ .

$x = - 6$

Step 3.5

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

$x + 3 = - (2 x + 9)$

Step 3.6

Simplify $- (2 x + 9)$ .

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Step 3.6.1

Rewrite.

$x + 3 = 0 + 0 - (2 x + 9)$

Step 3.6.2

Simplify by adding zeros.

$x + 3 = - (2 x + 9)$

Step 3.6.3

Apply the distributive property.

$x + 3 = - (2 x) - 1 \cdot 9$

Step 3.6.4

Multiply.

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Step 3.6.4.1

Multiply $2$ by $- 1$ .

$x + 3 = - 2 x - 1 \cdot 9$

Step 3.6.4.2

Multiply $- 1$ by $9$ .

$x + 3 = - 2 x - 9$

Step 3.7

Move all terms containing $x$ to the left side of the equation.

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Step 3.7.1

Add $2 x$ to both sides of the equation.

$x + 3 + 2 x = - 9$

Step 3.7.2

Add $x$ and $2 x$ .

$3 x + 3 = - 9$

Step 3.8

Move all terms not containing $x$ to the right side of the equation.

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Step 3.8.1

Subtract $3$ from both sides of the equation.

$3 x = - 9 - 3$

Step 3.8.2

Subtract $3$ from $- 9$ .

$3 x = - 12$

Step 3.9

Divide each term in $3 x = - 12$ by $3$ and simplify.

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Step 3.9.1

Divide each term in $3 x = - 12$ by $3$ .

$\frac{3 x}{3} = \frac{- 12}{3}$

Step 3.9.2

Simplify the left side.

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Step 3.9.2.1

Cancel the common factor of $3$ .

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Step 3.9.2.1.1

Cancel the common factor.

$\frac{3 x}{3} = \frac{- 12}{3}$

Step 3.9.2.1.2

Divide $x$ by $1$ .

$x = \frac{- 12}{3}$

Step 3.9.3

Simplify the right side.

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Step 3.9.3.1

Divide $- 12$ by $3$ .

$x = - 4$

Step 3.10

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

$x = - 6, - 4$

Step 4

Exclude the solutions that do not make $| x + 3 | - 9 = 2 x$ true.

$x = - 4$