In the decimal representation of x,where 0 < x < 1,is the te

问题描述:

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.
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.
1个回答 分类:数学 2014-09-17

问题解答:

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选b.
题目是说,x是一个0到1之间的数,问当x以小数形式表示时,其十分位是否是非零数字.
先看1,16x是整数,那么1/16,2/16都可以,而1/16=0.0625,2/16=0.125,不能确定x的十分位到底是不是非零.
再看2,8x是整数,那么x至少等于1/8=0.125,十分位是非零数字.
综上,选b.
 
 
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