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题库 / OG2017Q-DS-272
Is x2 greater than x ?
(1) x2 is greater than 1.
(2) x is greater than -1.
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
题目分析：
（1） 如果~$x^2＞1$~，则有x>1或者x<-1。若x<-1,显然~$x^2$~为正数，大于x；若x>1，两边同时乘以x，不等号方向不变，有~$x^2＞x$~，题目得解。
（2） 如果~$x^2＞-1$~，例如x=0.5，满足条件2，但~$x^2=0.25＜0.5$~；又如x=2，满足条件2，~$x^2=4＞2$~，所以条件2无法判断。
因此，本题答案为（A），仅条件1可以解题，条件2不行。
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结论：x1