Question

How do you determine if `21` is a polynomial and if so, how do you identify if it is a monomial, binomial, or trinomial?

Answer 1

Look for the number of terms that are separated by + or - signs.

Explanation:

If 21 would written as `2xx 10 + 1 xx 1` it would be clear that the number is a binomial. The plus sign between the tens and the ones gives it away. So technically 21 is a binomial but for practical purposes it can be regarded as monomial as the two terms can be combined.

A monomial has only one term. Everything can be combine without a plus or a minus sign. such as 4x (`4 xx x)`

A binomial has two terms. There are unlike terms that cannot be combined. such as x + 4 there is one plus or minus sign.

A trinomial has three terms. There are three unlike terms that can not be combines such `x^2 + 4x + 4` there are two plus or minus signs.