One of the important tasks in mathematics is solving equations and inequalities. An equation is simply a statement that two algebraic expressions are equal. For instance, 5x + 2 and 3(x − 1) are examples of algebraic expression; and 5x + 2 = 7 or 5x + 2 = 3(x − 1) are examples of equation. The task is to find the value of x that makes the given equation true when x is replaced by it.

Similarly, an algebraic inequality is a mathematical statement that an expression is less than (or greater than) another expression. For instance, 5x + 2 < 7 or 5x + 2 > 3(x − 1) are examples of algebraic inequalities. The related task is to find possible values of x that make the given inequality true when x is replaced by the values. These will be discussed in this unit.