请教各位两道数学题……GWD 4 Q4 Q5

sailing0831 · 发表于 2010-10-19 19:34:02

Q4:
For a nonnegative integer n, if the remainder is 1 when 2ⁿ is divided by 3, then which of the following must be true?

I.n is greater than zero.
II.3ⁿ = (-3)ⁿ
III.√2ⁿis an integer.

A.I only
B.II only
C.I and II
D.I and III
E.II and III

下面这道题没看懂~~好人给翻译一下吧……
Q5:
A certain club has 20 members.What is the ratio of the member of 5-member committees that can be formed from the members of the club to the number of 4-member committees that can be formed from the members of the club?

A.16 to 1
B.15 to 1
C.16 to 5
D.15 to 6
E.5 to 4
Answer:

sailing0831 · 发表于 2010-10-19 19:43:15

顶啊赐教吧

2010 · 发表于 2010-10-19 19:47:15

Q5:
A certain club has 20 members.某俱20人。
What is the ratio 求个比率
of 关于
the number[打错了吧不是member] of 5-member committees that can be formed from the members of the club [20人中选5个组成5人委员会的可能数]
to 比
the number of 4-member committees that can be formed from the members of the club [20人中选4个组成4人委员会的可能数]
?
就是两个组合数的比 C 5 20 / C 4 20 = 16:5

Q4: 中III.√2n是啥

sailing0831 · 发表于 2010-10-19 19:55:44

那个是 2的n次方再开根号~~~
原来是number
感激你！

sailing0831 · 发表于 2010-10-19 19:56:32

Q5:
A certain club has 20 members.某俱20人。
What is the ratio 求个比率
of 关于
the number[打错了吧不是member] of 5-member committees that can be formed from the members of the club [20人中选5个组成5人委员会的可能数]
to 比
the number of 4-member committees that can be formed from the members of the club [20人中选4个组成4人委员会的可能数]
?
就是两个组合数的比 C 5 20 / C 4 20 = 16:5

Q4: 中III.√2n是啥

-- by 会员 2010 (2010/10/19 19:47:15)

那个是 2的n次方再开根号~~~
谢谢谢谢谢谢

2010 · 发表于 2010-10-19 20:05:57

Q4
没啥好办法，写一串2的次方出来吧，2，4，8，16，32，64，128，256，512，。。。
会发现一个规律，2的奇数次方被3除余2，2的偶数次方被3除余1。
题中被3除余1，说明n是偶数 E.II and III
I.n is greater than zero. n=0可排出
II.3n = (-3)n
III.√2nis an integer.

哪的题啊，真蛋疼~

海诺薇拉 · 发表于 2010-10-19 20:08:28

第一题我当时也纠结了下。。。酱想，2^2除3的余数是1，指数多1余数就是2，再多1就是4，啊，也就是1 ，所以n就肯定是偶数啦~归纳归纳~

sailing0831 · 发表于 2010-10-19 20:17:52

Q4
没啥好办法，写一串2的次方出来吧，2，4，8，16，32，64，128，256，512，。。。
会发现一个规律，2的奇数次方被3除余2，2的偶数次方被3除余1。
题中被3除余1，说明n是偶数 E.II and III
I.n is greater than zero. n=0可排出
II.3n = (-3)n
III.√2nis an integer.

哪的题啊，真蛋疼~

-- by 会员 2010 (2010/10/19 20:05:57)

是GWD上的题呀~~~~几乎每一套都有那么一两道这么蛋疼的题。。。

sailing0831 · 发表于 2010-10-19 20:18:56

第一题我当时也纠结了下。。。酱想，2^2除3的余数是1，指数多1余数就是2，再多1就是4，啊，也就是1 ，所以n就肯定是偶数啦~归纳归纳~

-- by 会员海诺薇拉 (2010/10/19 20:08:28)

我每次做这种必须自己一个一个试的就很没底~~总觉得应该有什么方法的

请教各位两道数学题……GWD 4 Q4 Q5

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