Question

Factorise: 1-2a-2b-(a+b)^2

Answer 1

=1-2(a+b)-3(a+b)²

=1-3(a+b)+(a+b)-3(a+b)²

=1[1-3(a+b)]+(a+b)[1-3(a+b)]

=[1-3(a+b)][1+(a+b)]

=(1-3a-3b)(1+a+b)