Absolute Value Inequalities

An absolute value inequality is an inequality that has an absolute value sign with a variable inside.

Example 1:

Solve and graph.

|x – 7| < 3

To solve this sort of inequality, we need to break it into a compound inequality.

x – 7 < 3 AND x – 7 > –3

–3 < x – 7 < 3

Add 7 to each expression.

4 < x <10

The graph looks like this:

Some absolute value inequalities result in an "OR" inequality, rather than an "AND" inequality. The graphs of these will be two rays in opposite directions.

Example 2:

Solve and graph.

|x + 2| 4

Split into two inequalities.

x + 2 4 OR x + 2 –4

Subtract 2 from both sides of each inequality.

x 2 OR x –6

Multiply the second inequality by –1. Again, remember to reverse the direction.

x 2 OR x + 2 –4

Subtract 2 from both sides of the second inequality.

x 2 OR x – 6