谁对余数的题有把握帮我看看

bigbenzhang

In the decimal representation of x, where 0 < x < 1, is the tenths digit if x nonzero?

(1)     16x is an integer.

(2)     8x is an integer.

                  

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

答案是b

余数的题我好像一直不太会。nn帮忙。

smthbigur

穷举就可以了，给出了0<x<1 也就9个数字嗄，0－9

bigbenzhang

What is the remainder when the positive integer x is divided by 8?

(1)     When x is divided by 12, the remainder is 5.

(2)     When x is divided by 18, the remainder is 11.

                  

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

还有这个题。答案是E。

amumu

这句话是什么意思：is the tenths digit if x nonzero

skycynju

以下是引用bigbenzhang在2009/10/5 22:01:00的发言：

In the decimal representation of x, where 0 < x < 1, is the tenths digit if x nonzero?

(1)     16x is an integer.

(2)     8x is an integer.

                  

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

答案是b

余数的题我好像一直不太会。nn帮忙。

(1) 16x是integer,     如果tenths是0， 则0<16x<1.6,必定为1，此时x=0.0625，符合条件

                                如果tenths不是0，令x=0.5，可以满足,   所以条件1不能确定

（2）8x 是 integer， 如果tenths是0，则0<8x<0.8, 不能满足，所以x的tenths肯定不是0

切尔西

以下是引用amumu在2009/10/5 22:26:00的发言：
这句话是什么意思：is the tenths digit if x nonzero

小数点后面第一位

JJJooe

问题没打错么？怎么看不懂

amumu

以下是引用切尔西在2009/10/5 22:49:00的发言：

小数点后面第一位

这个我知道啊，但是问“小数点后面第一位”什么呢？

blythehu

貌似题写错了吧…

是不是：In the decimal representation of x, where 0< x< 1, is the tenths digit of x nonzero?
1) 16x is an integer
2) 8x is an integer

 

0<x<1
1. 16x is an integer => x 可以是 1/16, 2/16 ...... 15/16。
                1/16=0.0625,其十分位为0。其它几个数十分位非0。所以不确定。
2] 8x is an integer => x 可以是 1/8, 2/8 .... 7/8. 这些数十分位都是非0。所以确定肯定不是0。

B