PREP数学提问

Becca0223 · 发表于 2020-10-28 19:28:33

哪位大神帮忙看下这道题为何选第一个选项？
自己一个人琢磨的时候硬是琢磨不出来呀QAQ

If x, y, and z are integers and xy + z is an odd integer, is x an even integer?

(1) xy + xz is an even integer.
(2) y + xz is an odd integer.

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.

安東尼尼 · 发表于 2020-10-28 20:21:13

用條件1 xy+xz (even) 減掉題目的xy+z (odd)，
得到 xz-z = z*(x-1) (even-odd=odd)
--->可知 z=odd 與 x-1=odd
---> x=even
所以條件(1)充分

Becca0223 · 发表于 2020-11-7 00:09:45

安東尼尼发表于 2020-10-28 21:21:13

哇哦，豁然开朗，谢谢！

wendymai · 发表于 2020-11-7 14:33:33

安東尼尼发表于 2020-10-28 20:21
用條件1 xy+xz (even) 減掉題目的xy+z (odd)，
得到 xz-z = z*(x-1) (even-odd=odd)
--->可知 z=odd 與 x-1 ...

同意！

wendymai · 发表于 2020-11-7 14:35:58

昨天写prep也遇到了楼主这道道题，顺便问一下楼主下面这道题写对了吗？求问I为什么是对的~
是不是因为问题问的是could be true 而不是not be true?

If x > y2 > z4 , which of the following statements could be true?

I. x > y > z
II. z > y > x
III. x > z > y

A. I only

B. I and II only

C. I and III only

D. II and III only

E. I, II, and III (correct)

PREP数学提问

所属分类: GMAT考试

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