此题应该抄错了,应该是遗漏了一个x,∵ xy/(x+y) = 2∴ 1/x + 1/y = 1/2(3x - 5xy + 3y)/(-x + 3xy -y)=(3x - 5xy + 3y)/(-x + 3xy -y) [分子分母同除以xy,得]=(3/x + 3/y - 5)/(-1/x - 1/y + 3)=(3/2 -5)/(-1/2 + 3)...