Inequalities are mathematical sentences comparing two quantities that are not equal (or possibly not equal). There are five inequality symbols:
|x ≠ 3||x is not equal to 3|
|x < 3||x is less than 3|
|x > 3||x is greater than 3|
|x 3||x is less than or equal to 3|
|x 3||x is greater than or equal to 3|
The solutions of inequalities can be graphed on the number line as rays. If the inequality is "strict" ( or ), we use an open dot to indicate that the endpoint of the ray is not part of the solution. For the other types of inequalities ( and ), we use a closed dot to indicate that the endpoint is part of the solution.
See also solving linear inequalities.