26
Does the decimal equivalent of P/Q, where P and Q are positive integers, contain only a finite number of nonzero digits?
(1)
P>Q

(2)
Q=8


l
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient
l
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient
l
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
l
EACH statement ALONE is sufficient
l
Statements (1) and (2) TOGETHER are NOT sufficient

Answer

22
If X^2+Y^2=1, is X+Y=1?
(1)
XY=0

(2)
Y=0


l
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient
l
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient
l
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
l
EACH statement ALONE is sufficient
l
Statements (1) and (2) TOGETHER are NOT sufficient

Answer

第一题选E  吧     第二题选D

我认为第一题应该选B.因为1/8=0.125.所以N/8只要N为整数,就可以知道了.
第2题我认为选E,因为X+Y可能为-1

第一个选C,第二个选E

(1)Q=8,如果P=8，那么P/Q=1,所以B is not sufficient alone. 需要两个条件都满足。
(2)和楼上观点一致。

第一题三楼解释得对。分母的因数如果只是 2 和 5，化成小数就不会循环。四楼说如果 P = 8 时，P/Q = 1。这不是循环小数，所以 the number of nonzero digit is still finite。（就算没有小数点后的数，一用十进数字来表达就是 decimal representation。）

第二题也是像三楼所说。

反悔一下，我认为第1题应为D。因为两个条件都不能排除P/Q = 1，2，3.。。。。这样就不含有小数位，就不满足题干所说的包含有限个非零小数位的要求。

可能是整数不等于就是整数。做数学不应该只试几个数字。（补习社这样教人是害人的。我出题目有时就是特意出到如果只试某些数字就会得到错误的答案。）因为还有无限多个其他可能。这题要像三楼所说那样做。

楼上，你就就此题说此题吧。我还是坚持我的观点，If P=NQ,(N,P and Q are positive integers),then P/Q=N,  and N is a positivev integer. Do you think N is decimal equivalent  that contains only a finite number of nonzero digits is correct? I don't agree. Since N is a positive interger, it doesn't  contain any nonzero decimal digit. So the answer should be E. Right?

[ 本帖最后由 bzhou2001 于 2008-5-23 12:01 编辑 ]

You have not learned the meaning of decimal representation properly.  An integer, when it is written as 1, 2, 3, etc., is in decimal form.  For example, 1 = 1.000000 . . . .  It is just that the digits after the decimal point are all zeroes.  The answer is definite not E.

I know what I am talking about.  I write these kinds of questions, and I am a mathematician.  I hope you will trust me on this, as it is a serious misunderstanding about the meaning of decimal representation.  It may lead to another error when you actually take the test.