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
=10,则1 y
的值是( )3y−6xy−3x y+2xy−x
A. -2
B. 2
C. -2
D. 2
答
由已知
-1 x
=10,可知:y-x=10xy,1 y
∴
=3y−6xy−3x y+2xy−x
=3(y−x)−6xy y−x+2xy
=3×10xy−6xy 10xy+2xy
=2.24xy 12xy
故选B.