Factorize:

We have:

$x^{2}-x-156$

We have to split (-">−-1) into two numbers such that their sum is (-">−-1) and their product is (-">−-156).

Clearly, $-13+12=-1$ and $-13 \times 12=-156$

$\therefore x^{2}-x-156=x^{2}-13 x+12 x-156$

$=x(x-13)+12(x-13)$

$=(x-13)(x+12)$