若1/x-1/y=1,求3y-xy-3x/x-xy-y的值._数学解答

若1/x-1/y=1,求3y-xy-3x/x-xy-y的值.

人气：425 ℃　时间：2020-04-16 11:32:36

解答

1/x-1/y=1xy/x-xy/y=xyy-x=xy∴3y-xy-3x/x-xy-y=3（y-x）-xy/(x-y)-xy=3xy-xy/-xy-xy=2xy/-2xy=-1