An equation is a statement that asserts that two numbers or algebraic expressions are equal in value. An equation must include an equal sign. For example,

An identity is an equation involving algebraic expressions that is true for all values of the variables involved.

For example

An identity is an equation that is true for all values of the variables involved.

Example:

An inequality is a statement that one number or algebraic expression is less than (or greater than) another. There are four types of inequalities:

• The relation is less than is written
• is greater than is written ,
• is less than or equal to is written , and
• is greater than or equal to is written .