已知1x-1y=10,则3y−6xy−3xy+2xy−x的值是(  ) A.-2 B.2 C.-2 D.2

问题描述:

已知

1
x
-
1
y
=10,则
3y−6xy−3x
y+2xy−x
的值是(  )
A. -2
B. 2
C. -2
D. 2

由已知

1
x
-
1
y
=10,可知:y-x=10xy,
3y−6xy−3x
y+2xy−x
=
3(y−x)−6xy
y−x+2xy
=
3×10xy−6xy
10xy+2xy
=
24xy
12xy
=2

故选B.