In algebra, letters are used to stand for values that can change (variables) or for values that are not known (unknowns). A term is a number or letter on its own, or numbers and letters multiplied ...

Expressions like the following are called polynomials in one variable. 0, -5, 7 etc. are examples of constant polynomials. The constant polynomial 0 is also the zero polynomial. Others like 7x + 9 is ...