OG11 Data Sufficiency 146答案不解

grassgreen

Is n an integer?

(1)n square is an integer

(2)n square root is an integer.

Official Key: B

Reason for not choose (1): while n square is an integer, since n squre = n x n, then n square is an integer if n is an integer, it is unclear whether n is an integer here, NOT sufficient.

我觉得既然题目问n是否整数，（1）中说明n平方是整数。既然只有整数的平方才是整数，为什么不能因n2是整数反过来说明n是整数呢？

Thanks!

xiaoxinxin

根号3的平方是3，整数

oumengling

当n=根号3 时，n square 是整数，而n不是整数啊。。
我也是后来才想到的。。