先化简,再求值 (在线........等)

[(A^2-2AB+B^2) / (A^2-B^2)] /(1/a-1/b)
=[(A-B)^2/(A+B)(A-B)]/[(B-A)/(AB)]
=AB(A-B)/(B-A)(A+B)
=-AB/(A+B)
=-(√2+1)(√2-1)/(√2+1+√2-1)
=-(2-1)/2√2
=-√2/4

原式=((a-b)^2/(a+b)(a-b))/((b-a)/ab)
=-ab/(a+b)
=-(gen2+1)(gen2-1)/2gen2
=-gen2/4

根号2/4

AB/(A+B)
-（根号2）/4

((A^2-2AB+B^2) / (A^2-B^2)) /(1/a-1/b)
=(A-B)^2/(A^2-B^2)*AB/(B-A)
=-AB/(A+B)
=-(2-1)/(2根号2)
=-根号2/4

a=（根号2）＋1 B＝（根号2）-1

((A^2-2AB+B^2) / (A^2-B^2)) /(1/a-1/b）
=((A^2-2AB+B^2) / (A^2-B^2)) /[(B-A)/AB]
=(A-B)^2/(A-B)(A+B)/[(B-A)/AB]
=(A-B)/(A+B)/[(B-A)/AB]
=-AB/(A+B)
=-根号2/4