急求教费费6

delldell

If x and y are integers and xy<>0, what is the remainder when x is divided by y

1. when xi is divided by 2y, the remainder is 4

2. when x+y is divided by y, the remainder is 4

B

解释

1. x=2y*k+4, 举反例, 当Y=4, X=时, X/Y的余数为0.当Y=3, X=10, X/Y的余数1

2. x+y=y*k+4 则 x=(k-1)y+4, 所以x/y的余数为4

真不明白怎么由x=(k-1)y+4就直接推出余数为4, (1)中 x=2k*y+4和这个形式区别在哪里呀

warlord88

x+y=x/y+y/y, the remainder of y/y is 0, x/y's is 4,

condition 1 can result in at least two outcomes:for example,y=5,x=12 and y=6,x=11