Đáp án:
4a2b2−(a2+b2−1)24a2b2-(a2+b2-1)2
=(2ab)2−(a2+b2−1)2=(2ab)2-(a2+b2-1)2
=(2ab−a2−b2+1)(2ab+a2+b2−1)=(2ab-a2-b2+1)(2ab+a2+b2-1)
=[1−(a2+b2−2ab)][(a+b)2−1]=[1-(a2+b2-2ab)][(a+b)2-1]
=[1−(a−b)2](a+b−1)(a+b+1)=[1-(a-b)2](a+b-1)(a+b+1)
=(1−a+b)(1+a−b)(a+b−1)(a+b+1)=(1-a+b)(1+a-b)(a+b-1)(a+b+1)
