Question

已知1/a-1/b=3,求分式2a+3ab-2b/a-ab-b的值【已知a分之1减b分之1等于3，求（a-ab-b)分之（2a+3ab-2b)的值

已知1/a-1/b=3,求分式2a+3ab-2b/a-ab-b的值【已知a分之1减b分之1等于3，求（a-ab-b)分之（2a+3ab-2b)的值】

Answer 1

从第一条件得出b-a=3ab,a-b=-3ab
a-ab-b=-4ab
2a+3ab-2b=-3ab
结果是四分之三

Answer 2

因为1/a-1/b=3，所以(b-a)/ab=3,a-b=-3ab,a=b-3ab
(2a+3ab)/(a-ab-b)=(2b-6ab+3ab)/(-4ab)
=-(2b-3ab)/4ab=3/4-1/2a

Answer 3

/a-1/b=3,
(b-a)/ab=3
b-a=3ab
a-b=-3ab

(2a+3ab-2b)/(a-ab-b)
=[2(a-b)+3ab]/[(a-b)-ab]
=(-6ab+3ab)/(-3ab-ab)
=-3ab/(-4ab)
=3/4