Evaluate the following using suitable identities: $(998)^{3}$

Check whether $-2$ and $2$ are zeroes of the polynomial $x + 2$.

Which of the following expressions are polynomials in one variable and which are not? State reasons for your answer: $x^{10} + y^{3} + t^{50}$

Verify whether the following are zeroes of the polynomial indicated against them:
$p(x) = x^{2} - 1, x = 1, -1$

Verify: $x^{3}+y^{3}=(x+y)(x^{2}-xy+y^{2})$

Factorise $: 8 x^{3}+y^{3}+27 z^{3}-18 x y z$