x(y+1)+(y+1)=1999(x+1)(y+1)=19991999是质数,因数只有1和它本身.1999=1×1999=(-1)×(-1999)共有4种情况：x+1=1y+1=1999 解得x=0y=1998x+1=1999 y+1=1解得x=1998y=0x+1=-1y+1=-1999解得x=-2y=-20...