Question

已知a分之1减b分之1等于2分之1,求a-b分之ab的值

Answer 1

1/a-1/b=1/2
(b-a)/ab=1/2
ab=2(b-a)
ab/(a-b)
=[2(b-a)]/(a-b)
=[-2(a-b)]/(a-b)
=-2