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Solution - Absolute value equations

Exact form:

x = 3, 5

x=3 , 5

See steps

Step-by-step explanation

1. Rewrite the equation with one absolute value terms on each side

$| - x + 2 | - | 2 x - 7 | = 0$

Add $| 2 x - 7 |$ to both sides of the equation:

$| - x + 2 | - | 2 x - 7 | + | 2 x - 7 | = | 2 x - 7 |$

Simplify the arithmetic

$| - x + 2 | = | 2 x - 7 |$

2. 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
$| - x + 2 | = | 2 x - 7 |$
without the absolute value bars:

$\| x \| = \| y \|$	$\| - x + 2 \| = \| 2 x - 7 \|$
$x = + y$	$(- x + 2) = (2 x - 7)$
$x = - y$	$(- x + 2) = (- (2 x - 7))$
$+ x = y$	$(- x + 2) = (2 x - 7)$
$- x = y$	$- (- x + 2) = (2 x - 7)$

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:

$\| x \| = \| y \|$	$\| - x + 2 \| = \| 2 x - 7 \|$
$x = + y$ , $+ x = y$	$(- x + 2) = (2 x - 7)$
$x = - y$ , $- x = y$	$(- x + 2) = (- (2 x - 7))$

3. Solve the two equations for x

13 additional steps

$(- x + 2) = (2 x - 7)$

Subtract from both sides:

$(- x + 2) - 2 x = (2 x - 7) - 2 x$

Group like terms:

$(- x - 2 x) + 2 = (2 x - 7) - 2 x$

Simplify the arithmetic:

$- 3 x + 2 = (2 x - 7) - 2 x$

Group like terms:

$- 3 x + 2 = (2 x - 2 x) - 7$

Simplify the arithmetic:

$- 3 x + 2 = - 7$

Subtract from both sides:

$(- 3 x + 2) - 2 = - 7 - 2$

Simplify the arithmetic:

$- 3 x = - 7 - 2$

Simplify the arithmetic:

$- 3 x = - 9$

Divide both sides by :

$\frac{(- 3 x)}{- 3} = \frac{- 9}{- 3}$

Cancel out the negatives:

$\frac{3 x}{3} = \frac{- 9}{- 3}$

Simplify the fraction:

$x = \frac{- 9}{- 3}$

Cancel out the negatives:

$x = \frac{9}{3}$

Find the greatest common factor of the numerator and denominator:

$x = \frac{(3 \cdot 3)}{(1 \cdot 3)}$

Factor out and cancel the greatest common factor:

$x = 3$

8 additional steps

$(- x + 2) = - (2 x - 7)$

Expand the parentheses:

$(- x + 2) = - 2 x + 7$

Add to both sides:

$(- x + 2) + 2 x = (- 2 x + 7) + 2 x$

Group like terms:

$(- x + 2 x) + 2 = (- 2 x + 7) + 2 x$

Simplify the arithmetic:

$x + 2 = (- 2 x + 7) + 2 x$

Group like terms:

$x + 2 = (- 2 x + 2 x) + 7$

Simplify the arithmetic:

$x + 2 = 7$

Subtract from both sides:

$(x + 2) - 2 = 7 - 2$

Simplify the arithmetic:

$x = 7 - 2$

Simplify the arithmetic:

$x = 5$

4. List the solutions

$x = 3, 5$
(2 solution(s))

5. Graph

Each line represents the function of one side of the equation:
$y = | - x + 2 |$
$y = | 2 x - 7 |$
The equation is true where the two lines cross.

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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 with one absolute value terms on each side

2. Rewrite the equation without absolute value bars

3. Solve the two equations for x

4. List the solutions

5. Graph

Why learn this

Terms and topics

Related links

Solution - Absolute value equations

Step-by-step explanation

1. Rewrite the equation with one absolute value terms on each side

2. Rewrite the equation without absolute value bars

3. Solve the two equations for x

4. List the solutions

5. Graph

Why learn this

Terms and topics

Related links

Latest Related Drills Solved