若1a−1b=5,则分式2a+3ab−2ba−2ab−b的值为(  ) A.135 B.−35 C.35 D.1

问题描述:

1
a
1
b
=5,则分式
2a+3ab−2b
a−2ab−b
的值为(  )
A.
13
5

B.
3
5

C.
3
5

D. 1

1
a
1
b
=5,
b−a
ab
=5,
∴a-b=-5ab,
∴原式=
2(a−b)+3ab
(a−b)−2ab

=
2×(−5ab)+3ab
−5ab−2ab

=
−7ab
−7ab

=1.
故选D.