:如果XY/X+Y=2,求代数式3X-5Y+3Y/-X+3XY-Y的值为 没错!

问题描述:

:如果XY/X+Y=2,求代数式3X-5Y+3Y/-X+3XY-Y的值为 没错!

XY/X+Y=2
∴xy=2(x+y)
3X-5 x Y+3Y/-X+3XY-Y
=[3(x+y)-5xy]/[-(x+y)+3xy]
=[3(x+y)-10(x+y)]/[-(x+y)+6(x+y)]
=-7/5