If $p(3) = 0$ for a polynomial $p(x)$,state one factor of $p(x)$.

Are the following expressions polynomials? Justify your answer:
$\frac{1}{7} a^{3}-\frac{2}{\sqrt{3}} a^{2}+4 a-7$

Which of the following expressions are polynomials in one variable and which are not? State the reason for your answer. If the given expression is a polynomial,state whether it is a polynomial in one variable or not: $5 x^{2}-7 x+3 \sqrt{x}$

Expand $(5x - 7y - z)^2$.

State whether the following statement is True or False. Justify your answer.
$A$ binomial may have degree $5$.

If $x+y=12$ and $xy=27$,find the value of $x^{3}+y^{3}$.