### Theory:

Any algebraic expression with two terms is called a binomial expression.
Example:
$2x+3y$, here we have two terms, they are $$2x$$ and $$3y$$. Thus this expression is called as binomial expression

$3{x}^{2}y$$-7\mathit{xy}$ is a binomial

$3{x}^{2}y\phantom{\rule{0.147em}{0ex}}+\left(-7\mathit{yx}\right)\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}3{x}^{2}y\phantom{\rule{0.147em}{0ex}}-7\mathit{yx}$ is also a binomial
Like we have already seen in addition and subtraction of algebraic expressions, when adding or subtracting only the like terms are added or subtracted.

Let us look at an example and discuss the terms of a binomial and a degree of a term.
It is very important to keep in mind that a binomial expression has only two terms. This is the reason why it is called a binomial (prefix 'bi' stands for 'two').
Example:
$2x+3y$ here the terms of the binomial are $2x$ and $3y$
Degree in an algebraic expression is the sum of the exponents of the variables in the expression.
Example:
$7x{y}^{2}-3{y}^{2}z$  here

 terms of the binomial $7{x}^{2}y$ $-3{y}^{2}z$ coefficients $$7$$ $$-3$$ degrees of the terms $$2+ 1 = 3$$ $$2 + 1 = 3$$