Find the zero of the polynomial in each of the following cases

$p(t)=7 t-21$

For $p(x)=x^{3}+9 x^{2}+26 x+24$ $p(-2)=\ldots \ldots \ldots$

Expand

$(2 x-3)(2 x+5)$

Simplify $(2 x-5 y)^{3}-(2 x+5 y)^{3}$

Factorise

$8 x^{3}-26 x^{2}+13 x+5$

Factorise the following:

$9 y^{2}-66 y z+121 z^{2}$