x=y=2/5x+2xy+y分之2x-3xy+2y的值为1(如果我没计算错的话)
由1/X+1/Y=5知X+Y=5XY 故X+2XY+Y=7XY,2X+2Y-3XY=2(X+Y)-3XY=10XY-3XY=7XY所以X+2XY+Y分之2X-3XY+2Y=1
1/x+1/y=(x+y)/(xy)=5x+y=5xy (2x-3xy+2y)/(x+2xy+y)=(2*5xy-3xy)/(5xy+2xy)=(10-3)/(5+2)=1