2(a+1)(a-1)-(a+b)(a-b)-5b=3
2a^2-2-a^2+b^2-5b=3
a^2+b^2-5b=5
a^2=a^2+b^2-5b=5
(a+2b)(a-2b)
=a^2-4b^2
=-b^2+5b+5-4b^2
=-5b^2+5b+5
题目有误,不能求出答案
2(a+1)(a-1)-(a+b)(a-b)-5b=3
2a^2-2-a^2+b^2-5b=3
a^2+b^2-5b=5
a^2=a^2+b^2-5b=5
(a+2b)(a-2b)
=a^2-4b^2
=-b^2+5b+5-4b^2
=-5b^2+5b+5
题目有误,不能求出答案