[求助]几道数学题求助,答案错还是我错！！

xixi86813

the intergers m and p are such that 1<m<p and m is not a factor of p. if r is the remainder when p is divided by m, is r >1?

1. the greast common factor of m and p is 2,

2. the least common mutiple of m and p is 30.

My choice is D,  but the answer is A

through the second sentence we can sure that the remaider  r is always 1, so why the answer is A?? 

2.

on the number line, the distance between point A and C is 5, and the distance between B and C is 20, does C lie between A and B?

1. the distance between point A and B is 25

2. A lies to the left of point B.

My choice is D and the answer is A??? Is it wrong?

[此贴子已经被作者于2009-1-10 15:19:05编辑过]

门萨来了

the intergers m and p are such that 1<m<p and m is not a factor of p. if r is the remainder when p is divided by m, is r >1?

1. the greast common factor of m and p is 2,

2. the least common mutiple of m and p is 30.

My choice is D,  but the answer is A

through the second sentence we can sure that the remaider  r is always 1, so why the answer is A?? 

2.中M和P的最小公倍数是30,不代表M*P=30,除非条件说M和P是互质的. 所以不能确定P/M的余数

1中说最大公约数是2,则M=2*a, P=2*b, (a.b为质因子),

除了2之外的质数向除余数都大于1哈====> A

门萨来了

2.

on the number line, the distance between point A and C is 5, and the distance between B and C is 20, does C lie between A and B?

1. the distance between point A and B is 25

2. A lies to the left of point B.

第2种情况: C=0, A=5, B=20,满足条件2,但是却无法得出C在A B中间

quien

我的思路：

第一题，（1）M和P的最大公约数是2，两个肯定都是偶数，两者不能整除，相差的数肯定是偶数，余数最小是2（2）举个反例，5和6，余数是1

第二题2)C----A-----B,A在B左边，但C不在它们之间啊

[此贴子已经被作者于2009-1-10 16:37:23编辑过]

xixi86813

我都明白了，谢谢楼上们的解答！！

[此贴子已经被作者于2009-1-10 16:48:27编辑过]

xixi86813

看来数学就是小点的疏忽就酿成大错啊...