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Solution - Absolute value equations

Exact form:

f = \frac{3}{8}

f=\frac{3}{8}

Decimal form:

f = 0.375

f=0.375

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
$| f - \frac{3}{4} | = | f |$
without the absolute value bars:

$\| x \| = \| y \|$	$\| f - \frac{3}{4} \| = \| f \|$
$x = + y$	$(f - \frac{3}{4}) = (f)$
$x = - y$	$(f - \frac{3}{4}) = - (f)$
$+ x = y$	$(f - \frac{3}{4}) = (f)$
$- x = y$	$- (f - \frac{3}{4}) = (f)$

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:

$\| x \| = \| y \|$	$\| f - \frac{3}{4} \| = \| f \|$
$x = + y$ , $+ x = y$	$(f - \frac{3}{4}) = (f)$
$x = - y$ , $- x = y$	$(f - \frac{3}{4}) = - (f)$

2. Solve the two equations for f

4 additional steps

$(f + \frac{- 3}{4}) = f$

Subtract from both sides:

$(f + \frac{- 3}{4}) - f = f - f$

Group like terms:

$(f - f) + \frac{- 3}{4} = f - f$

Simplify the arithmetic:

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

Simplify the arithmetic:

$\frac{- 3}{4} = 0$

The statement is false:

$\frac{- 3}{4} = 0$

The equation is false so it has no solution.

13 additional steps

$(f + \frac{- 3}{4}) = - f$

Add to both sides:

$(f + \frac{- 3}{4}) + f = - f + f$

Group like terms:

$(f + f) + \frac{- 3}{4} = - f + f$

Simplify the arithmetic:

$2 f + \frac{- 3}{4} = - f + f$

Simplify the arithmetic:

$2 f + \frac{- 3}{4} = 0$

Add to both sides:

$(2 f + \frac{- 3}{4}) + \frac{3}{4} = 0 + \frac{3}{4}$

Combine the fractions:

$2 f + \frac{(- 3 + 3)}{4} = 0 + \frac{3}{4}$

Combine the numerators:

$2 f + \frac{0}{4} = 0 + \frac{3}{4}$

Reduce the zero numerator:

$2 f + 0 = 0 + \frac{3}{4}$

Simplify the arithmetic:

$2 f = 0 + \frac{3}{4}$

Simplify the arithmetic:

$2 f = \frac{3}{4}$

Divide both sides by :

$\frac{(2 f)}{2} = \frac{(\frac{3}{4})}{2}$

Simplify the fraction:

$f = \frac{(\frac{3}{4})}{2}$

Simplify the arithmetic:

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

$f = \frac{3}{8}$

3. Graph

Each line represents the function of one side of the equation:
$y = | f - \frac{3}{4} |$
$y = | f |$
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 without absolute value bars

2. Solve the two equations for f

3. 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 f

3. Graph

Why learn this

Terms and topics

Related links

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