有无数组解.由于10=1X10=2X5 (x-y)(x+y-20)=101）x-y=1,x+y-20=10 解得x=31/2,y=29/2；2）x-y=2,x+y-20=5 解得x=27/2,y=23/2；3）x-y=5,x+y-20=2 解得x=27/2,y=17/2；4）x-y=10,x+y-20=1 解得x=31/2,y=11/2.有理数解...