Write the degree of the following polynomial: $x^{8}-6561$.

Factorise $27 x^{3}-y^{3}+64 z^{3}+36 x y z$.

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: $\pi x^{2}-\sqrt{3} x+11$

Write the following cube in expanded form:
$(2a - 5b)^3$

Determine the degree of the following polynomial:
$x^{3}-9x+3x^{5}$

Factorise the following expression: $8x^3 + 343y^3 + 84x^2y + 294xy^2$.