a分之1 减 b分之1 = 3,求分式（a-ab-b）分之（2a+3ab-2b）的值._数学解答

a分之1 减 b分之1 = 3,求分式（a-ab-b）分之（2a+3ab-2b）的值.

人气：356 ℃　时间：2020-02-21 01:14:30

解答

∵ 1/a-1/b=3
∴ b-a=3ab
a-ab-b=a-b-ab
=-3ab-ab
=-4ab
2a+3ab-2b=2(a-b)+3ab
=2×(-3ab)+3ab
=-3ab
∴原式=-4ab/(-3ab)
= 4/3