Factorise: x3−x2+ax+x−a−1
x3 – x2 + ax + x – a – 1
x3 – x2 + ax + x – a – 1
= x3 – x2 + ax – a + x – 1
= x2(x – 1) + a (x – 1) + 1 (x – 1)
= (x – 1) (x2 + a + 1)