Pre-Algebra Examples

$| x | + 4 > 8$

Step 1

Write

$| x | + 4 > 8$ as a piecewise.

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Step 1.1

To find the interval for the first piece, find where the inside of the absolute value is non-negative.

$x \geq 0$

Step 1.2

In the piece where

$x$ is non-negative, remove the absolute value.

$x + 4 > 8$

Step 1.3

To find the interval for the second piece, find where the inside of the absolute value is negative.

$x < 0$

Step 1.4

In the piece where

$x$ is negative, remove the absolute value and multiply by

$- 1$ .

$- x + 4 > 8$

Step 1.5

Write as a piecewise.

${\begin{cases} x + 4 > 8 & x \geq 0 \\ - x + 4 > 8 & x < 0 \end{cases}$

Step 2

Move all terms not containing

$x$ to the right side of the inequality.

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Step 2.1

Subtract

$4$ from both sides of the inequality.

$x > 8 - 4$

Step 2.2

Subtract

$4$ from

$8$ .

$x > 4$

Step 3

Solve

$- x + 4 > 8$ for

$x$ .

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Step 3.1

Move all terms not containing

$x$ to the right side of the inequality.

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Step 3.1.1

Subtract

$4$ from both sides of the inequality.

$- x > 8 - 4$

Step 3.1.2

Subtract

$4$ from

$8$ .

$- x > 4$

Step 3.2

Divide each term in

$- x > 4$ by

$- 1$ and simplify.

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Step 3.2.1

Divide each term in

$- x > 4$ by

$- 1$ . When multiplying or dividing both sides of an inequality by a negative value, flip the direction of the inequality sign.

$\frac{- x}{- 1} < \frac{4}{- 1}$

Step 3.2.2

Simplify the left side.

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Step 3.2.2.1

Dividing two negative values results in a positive value.

$\frac{x}{1} < \frac{4}{- 1}$

Step 3.2.2.2

Divide

$x$ by

$1$ .

$x < \frac{4}{- 1}$

Step 3.2.3

Simplify the right side.

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Step 3.2.3.1

Divide

$4$ by

$- 1$ .

$x < - 4$

Step 4

Find the union of the solutions.

$x < - 4$ or

$x > 4$

Step 5

The result can be shown in multiple forms.

Inequality Form:

$x < - 4 or x > 4$

Interval Notation:

$(- \infty, - 4) \cup (4, \infty)$

Step 6