Factorise the following expression:

$x^2-y^2-2y-1$

Factorise the following expression:

$p^2-4pq+4q^2-r^2$

Factorise the following expression:

$9x^2-y^2+4y-4$

Factorise the following expression:

$4a^2-4b^2+4a+1$

Factorise the following expression:

$625-p^4$

Factorise the following expression:

$5y^5-405y$

Factorise the following expression:

$x^4-y^4+x^2-y^2$

Factorise the following expression:

$64a^2-9b^2+42bc-49c^2$

Factorise the following polynomial:

$x^2+3x+2$