Question

1/a-1/b=3,求（3a+4ab-3b）/（a-2ab-b）的值

Answer 1

1/a-1/b=3

(b-a)/(ab)=3

b-a=3ab

a-b=-3ab

(3a+4ab-3b)/(a-2ab-b)

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

=(-9ab+4ab)/(-3ab-2ab)

=(-5ab)/(-5ab)

=1