To know which of the following expressions are polynomials, let us look at the definition of a polynomial:
Polynomial is derived from poly- (which means "many") and -nomial (meaning "term"), so it says "many terms".
For an instance: is a polynomial, but is not a polynomial because it contains single term only.
We must keep in mind that in polynomial it can have variables, constants, and exponents but it can never have division by a variable.
Now lets, look at the
since it has got one term it can not be a polynomial.
: it has got <em>more than one term</em> therefore, <em>it is a polynomial. </em>
: again it has got just one term so it is not a polynomial.
: Since it has got <em>more than one term</em>, so again<em> it is a polynomial. </em>