已知1/a-1/b=2,求2a-ab-2b/a-3a-b的值

已知1/a-1/b=2,求2a-ab-2b/a-3a-b的值
已知1/a-1/b=2,求2a-ab-2b/a-3a-b的值

已知1/a-1/b=2,求2a-ab-2b/a-3a-b的值
1/a-1/b=2
(b-a)/ab=2
b-a=2ab
a-b=-2ab
(2a-ab-2b)/(a-3ab-b)
=(-4ab-ab)/(-2ab-3ab)
=-5ab/(-5ab)
=1

(2a-ab-2b)/(a-3ab-b)——把分子分母同时除以ab
=(2/b-1-2/a)/(1/b-3-1/a)
=[-2(1/a-1/b)-1]/[-(1/a-1/b)-3]
=(-4-1)/(-2-3)
=(-5)/(-5)
=1