If $x^{2}-10 x+21=(x+m)(x+n)$ then $m+n=\ldots \ldots \ldots$

Factorise :

$x^{2}+9 x+18$

Factorise the following:

$1-64 a^{3}-12 a+48 a^{2}$

By remainder Theorem find the remainder, when $p(x)$ is divided by $g(x),$ where

$p(x)=x^{3}-6 x^{2}+2 x-4, \quad g(x)=1-\frac{3}{2} x$

Factorise $: 4 x^{2}+4 x y-3 y^{2}$

Find the zeroes of the polynomial:

$p(x)=(x-2)^{2}-(x+2)^{2}$