In

Algebra, an expression is a set of one or more

terms. For instance, in the

equation
7x - 2y + 3z = 3x + 7y - 2z

7x - 2y + 3z is an expression, as is 3x + 7y - 2z.

However, 7x - 2y + 3z = 3x + 7y - 2z is not in and of itself an expression.

These expressions are given diffrent names depending on the number of terms involved.

An expression with one

term, like 7x alone, is called a

monomial.

An expression with two

terms, like 3x + 4y, is called a

binomial.

An expression with three

terms, like 5x + 8z - 3xz, is called a

trinomial.