Factorise the following.

$x^3-x^2+ax+x-a-1$

Factorise the following.

$ab\left(c^2+1\right)+c\left(a^2+b^2\right)$

Factorise the following.

$a^3-a^2+xa+a-x-1$

Factorise the following.

$6a^{3}b+3a^2{b}^2-2a^{2}b-a{b}^2$

Factorise the following.

$a^3+ab(1-2a)-2b^2$

Factorise the following.

$\left(p^2+1\right)q-p^2-q^2$

Factorise:

$x^2+4x+4$