1,设甲队M天完成:M/2*X+M/2*Y=2 M=4/(X+Y) 甲队完成任务需要4/(X+Y)天 设乙队N天完成:N=1/X+1/Y N=(X+Y)/(XY) 乙队完成任务需要(X+Y)/(XY)天.2,甲队完成任务需要天数-乙队完成任务需要天数 =4/(X+Y)-(X+Y)/(XY) =(4XY-(X+Y)^2)/[(X+Y)XY] =(4XY-X^2-2XY-Y^2)/[(X+Y)XY] =(-X^2+2XY-Y^2)/[(X+Y)XY] =-(X-Y)^2/[(X+Y)XY] 因为X不等于Y,所以:-(X-Y)^2/[(X+Y)XY]