Question

x2 - 1 - 2y - y Factorise it​

Answer 1

$x {}^{2} - 1 - 2y - y \\ x {}^{2} - (y + 2y + 1) \\ x {}^{2} - (y + 1) {}^{2} \\ (x + (y + 1)) (x - (y + 1))$

Answer : (x+y+1)(x-y-1)