GWD MATH 28 Q33&Q34 求教~~

viridian · 发表于 2011-6-27 21:50:02

Q33:
150, 200, 250, n

Which of the following could be the median of the 4 integers listed above?

I.175
II.215
III.235

A.I only
B.II only
C.I and II only
D.II and III only
E.I, II, and III
Answer: C
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Q34:
The operation Θ is defined by x Θ y =
1/x +1/y for all nonzero numbers x and y.If z is a number greater than 1, which of the following must be true?

I.x Θ (-z) = 0
II.z Θ (z/z-1)= 1
III. (2/z)Θ (2/z)= z

第二个和第三都轻松带入都可以得到答案..第一个由于-Z<0.。不知道该怎么处理了..= =!! 望NN解答~

viridian · 发表于 2011-6-28 07:38:16

dxt678 · 发表于 2011-6-28 09:25:49

-- by 会员 viridian (2011/6/28 7:38:16)

第34题的选项X换成Z就对了。

Rainbeauty · 发表于 2011-6-28 12:51:58

34第一个选项y换成z

viridian · 发表于 2011-6-28 12:52:54

Q33有人可以解答咩~~~~

chebing · 发表于 2011-6-28 13:20:09

把150, 200, 250从小到大排列，然后插入n，则n只有两个位置，n 150 200 250,或150 200 250 n，则第一种情况，中值为175:；第二种为225

garlicwu · 发表于 2011-6-28 13:55:41

Q34: 是 I.x Θ (-z) = 0 还是 I.z Θ (-z) = 0 ？后者的话负号可以移出括号，I 成立吧

Q33：四种可能性
1. n, 150, 200, 250: midean = 175
2. 150, n, 200, 250: 175 < median < 200
3. 150, 200, n, 250: 200 < median < 225
4. 150, 200, 250, n: median = 225

所以 III 235 不可能

garlicwu · 发表于 2011-6-28 13:59:28

Q33 换个角度，求median的min和max

min： n, 150, 200, 250: midean = 175
max：150, 200, 250, n: median = 225

所以：175 <= median <= 225

viridian · 发表于 2011-6-28 18:53:46

谢谢大家！！

GWD MATH 28 Q33&Q34 求教~~

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