An algebraic expression is not a polynomial when:
i) the algebraic expression has a variable as the denominator.
Eg. \(x^{3} + 2x^{2}+ \frac{1}{x}+1\)
ii) the algebraic expression has the square root of a variable.
Eg. \(x^{3}+2 x^{2} + \frac{1}{ \sqrt{x} } +1\)
