Enter an equation or problem

Camera input is not recognized!

Solution - Absolute value equations

Exact form:

x = - 5, - \frac{4}{3}

x=-5 , -\frac{4}{3}

Mixed number form:

x = - 5, - 1 \frac{1}{3}

x=-5 , -1\frac{1}{3}

Decimal form:

x = - 5, - 1.333

x=-5 , -1.333

See steps

Step-by-step explanation

1. Rewrite the equation without absolute value bars

Use the rules:
$| x | = | y |$ → $x = \pm y$ and $| x | = | y |$ → $\pm x = y$
to write all four options of the equation
$| 2 x - 1 | = | 4 x + 9 |$
without the absolute value bars:

$\| x \| = \| y \|$	$\| 2 x - 1 \| = \| 4 x + 9 \|$
$x = + y$	$(2 x - 1) = (4 x + 9)$
$x = - y$	$(2 x - 1) = - (4 x + 9)$
$+ x = y$	$(2 x - 1) = (4 x + 9)$
$- x = y$	$- (2 x - 1) = (4 x + 9)$

When simplified, equations $x = + y$ and $+ x = y$ are the same and equations $x = - y$ and $- x = y$ are the same, so we end up with only 2 equations:

$\| x \| = \| y \|$	$\| 2 x - 1 \| = \| 4 x + 9 \|$
$x = + y$ , $+ x = y$	$(2 x - 1) = (4 x + 9)$
$x = - y$ , $- x = y$	$(2 x - 1) = - (4 x + 9)$

2. Solve the two equations for x

13 additional steps

$(2 x - 1) = (4 x + 9)$

Subtract from both sides:

$(2 x - 1) - 4 x = (4 x + 9) - 4 x$

Group like terms:

$(2 x - 4 x) - 1 = (4 x + 9) - 4 x$

Simplify the arithmetic:

$- 2 x - 1 = (4 x + 9) - 4 x$

Group like terms:

$- 2 x - 1 = (4 x - 4 x) + 9$

Simplify the arithmetic:

$- 2 x - 1 = 9$

Add to both sides:

$(- 2 x - 1) + 1 = 9 + 1$

Simplify the arithmetic:

$- 2 x = 9 + 1$

Simplify the arithmetic:

$- 2 x = 10$

Divide both sides by :

$\frac{(- 2 x)}{- 2} = \frac{10}{- 2}$

Cancel out the negatives:

$\frac{2 x}{2} = \frac{10}{- 2}$

Simplify the fraction:

$x = \frac{10}{- 2}$

Move the negative sign from the denominator to the numerator:

$x = \frac{- 10}{2}$

Find the greatest common factor of the numerator and denominator:

$x = \frac{(- 5 \cdot 2)}{(1 \cdot 2)}$

Factor out and cancel the greatest common factor:

$x = - 5$

12 additional steps

$(2 x - 1) = - (4 x + 9)$

Expand the parentheses:

$(2 x - 1) = - 4 x - 9$

Add to both sides:

$(2 x - 1) + 4 x = (- 4 x - 9) + 4 x$

Group like terms:

$(2 x + 4 x) - 1 = (- 4 x - 9) + 4 x$

Simplify the arithmetic:

$6 x - 1 = (- 4 x - 9) + 4 x$

Group like terms:

$6 x - 1 = (- 4 x + 4 x) - 9$

Simplify the arithmetic:

$6 x - 1 = - 9$

Add to both sides:

$(6 x - 1) + 1 = - 9 + 1$

Simplify the arithmetic:

$6 x = - 9 + 1$

Simplify the arithmetic:

$6 x = - 8$

Divide both sides by :

$\frac{(6 x)}{6} = \frac{- 8}{6}$

Simplify the fraction:

$x = \frac{- 8}{6}$

Find the greatest common factor of the numerator and denominator:

$x = \frac{(- 4 \cdot 2)}{(3 \cdot 2)}$

Factor out and cancel the greatest common factor:

$x = \frac{- 4}{3}$

3. List the solutions

$x = - 5, - \frac{4}{3}$
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
$y = | 2 x - 1 |$
$y = | 4 x + 9 |$
The equation is true where the two lines cross.

How did we do?

Please leave us feedback.

Why learn this

We encounter absolute values almost daily. For example: If you walk 3 miles to school, do you also walk minus 3 miles when you go back home? The answer is no because distances use absolute value. The absolute value of the distance between home and school is 3 miles, there or back.
In short, absolute values help us deal with concepts like distance, ranges of possible values, and deviation from a set value.

Solution - Absolute value equations

Step-by-step explanation

1. Rewrite the equation without absolute value bars

2. Solve the two equations for x

3. List the solutions

4. Graph

Why learn this

Terms and topics

Related links

Solution - Absolute value equations

Step-by-step explanation

1. Rewrite the equation without absolute value bars

2. Solve the two equations for x

3. List the solutions

4. Graph

Why learn this

Terms and topics

Related links

Latest Related Drills Solved