Question

因式分解(ab+1)的平方--(a+b)的平方

Answer 1

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

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