Evaluate $(215)^{2}$.

Using a suitable identity,evaluate the following:
$999^{2}$

Is the following expression a polynomial? Justify your answer: $1-\sqrt{5x}$

By using the factor theorem,show that $(x-3)$ is a factor of the polynomial $p(x) = 12x^3 - 31x^2 - 18x + 9$ and then factorise the polynomial.

Find the value of the polynomial $x^{2}-7x+12$ at $x=-2$.

State whether the following statement is true or false:
The zero of the polynomial $2x + 3$ is $\frac{3}{2}$.