Binomials are of the form a(xi^mi...xj^mj) + b(xi^ni...xj^nj)
Distributive property is used to multiply two or more binomial.
Example:
(2x+y)(3x+y)
Apply distributive law:
(2x+y)3x + (2x+y)y
Again applying distributive law:
2x*3x + 3xy + 2xy + y*y
6x^2 + 5xy + y^2