【（a²+b²/a²-b²）-（a-b/a+b）】÷2ab/（a-b）（a+b）²=[(a^2+b^2)/(a+b)(a-b)-(a-b)^2/(a+b)(a-b)]÷2ab/（a-b）（a+b）²=(a^2+b^2-a^2+2ab-b^2)/(a+b)(a-b)*(a-b)(a+b)^2/2ab=2ab*...