a+b/1-a-b/1+1——则到底是什么意思哦.（a+b分之1）-（a-b分之1）+1[1/(a+b)-1/(a-b)+1]*(a²-b²)
=(a²-b²)/(a+b)-(a²-b²)/(a-b)+(a²-b²)
=[(a+b)(a-b)/(a+b)]-[(a+b)(a-b)/(a-b)]+(a²-b²)
=(a-b)-(a+b)+(a²-b²)
=-2b+a²-b²
=a²-b²-2b