Two real numbers or two algebraic expressions related by the symbols form an inequality.
An inequality is said to be linear if each variable occurs in the first degree only and there is no term involving the product of the variables.
If & are real numbers, such that then the set of all real numbers such that is called an open interval and is denoted by .
If & are real numbers such that , then the set of all real numbers such that is called a closed interval and is denoted by .
Solution of an inequality:
The value of , which make an inequality a true statement, are called solutions of the inequality.