Algebra Examples

$| x | > 6$

Step 1

Write $| x | > 6$ 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.

$x > 6$

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 $- 1$ .

$- x > 6$

Step 1.5

Write as a piecewise.

${\begin{cases} x > 6 & x \geq 0 \\ - x > 6 & x < 0 \end{cases}$

Step 2

Find the intersection of $x > 6$ and $x \geq 0$ .

$x > 6$

Step 3

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

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Step 3.1

Divide each term in $- x > 6$ by $- 1$ . When multiplying or dividing both sides of an inequality by a negative value, flip the direction of the inequality sign.

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

Step 3.2

Simplify the left side.

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Step 3.2.1

Dividing two negative values results in a positive value.

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

Step 3.2.2

Divide $x$ by $1$ .

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

Step 3.3

Simplify the right side.

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Step 3.3.1

Divide $6$ by $- 1$ .

$x < - 6$

Step 4

Find the union of the solutions.

$x < - 6$ or $x > 6$

Step 5

Convert the inequality to interval notation.

$(- \infty, - 6) \cup (6, \infty)$

Step 6