Question

急求因式分解题（1－a2)(1－b2)－4ab

Answer 1

=1-a^2-b^2+a^2b^2-4ab

=(a^2b^2-2ab+1) - (a^2+b^2+4ab)

=(ab-1)^2-(a+b)^2

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