Out of the following algebraic expressions,
A binomial is an algebraic expression which has two terms.
9×a+a=10a which is a monomial.
3a×2b×c=6abc which is a monomial.
6b2+5a+c has three terms, 6b2, 5a and c. So it is a trinomial.
5(a2+b)=5a2+5b has two terms, 5a2 and 5b. So it is a binomial.