就要留，换裤了，华丽丽地杯具了。。一些狗

dearsissi

奥特曼的考古简直无敌了

samalex

数列，a_0=3， a_(n+1)=2*a_n -1 求a_20-a_19。 答案是2^19

个人意见:
   a_(n+1) = 2*a_n - 1
 等价:   a_(n+1) - 1 = 2 * (a_n - 1)
     设 b_n = a_n - 1   .............
     则 b_(n + 1) = 2 b_n
    因为 a_0 = 3
    所以 b_0 = a_0 -1  = 2^1
             b_1 = 2b_0   = 2^2
             b_2 = 2b_1   = 2^3
             ...
             b_n = 2^(n+1)
    因为 : a_n  = b_n + 1
    所以   a_20 - a_19 = 2^21 + 1 - 2^20 - 1
                                    = 2^20
请大牛 指正.

zetsubo

数列，a_0=3， a_(n+1)=2*a_n -1 求a_20-a_19。 答案是2^19

个人意见:
   a_(n+1) = 2*a_n - 1
 等价:   a_(n+1) - 1 = 2 * (a_n - 1)
     设 b_n = a_n - 1   .............
     则 b_(n + 1) = 2 b_n
    因为 a_0 = 3
    所以 b_0 = a_0 -1  = 2^1
             b_1 = 2b_0   = 2^2
             b_2 = 2b_1   = 2^3
             ...
             b_n = 2^(n+1)
    因为 : a_n  = b_n + 1
    所以   a_20 - a_19 = 2^21 + 1 - 2^20 - 1
                                    = 2^20
请大牛 指正.

-- by 会员 samalex (2010/9/16 23:06:39)

我也觉得你这个答案对

桑子夏

看了一下你的AA，这是我写的。我24考，就当做练习。


The argument from the information technology department of an advertising firm recommends the company to invest on the most powerful and advanced information technology to maximize employee productivity. Several logic fallacies have been presented in this argument to make it not fully convincing. By pointing out a way to improve employee productivity and recommending heavy investment, the argument blocks out other options, and ignores the altitude of improvement and marginal cost and benefits. Lastly, it fails to identify the nature of the business and the degree of need in terms of employee productivity.

Information technology can improve employee productivity; however drawing a simple conclusion that the company should invest heavily on it precludes the possibility of other alternatives that also drive the productivity up. For an advertising company, employee productivity is influenced by several factors such as working environment, vertical integration (from idea to product), cost consciousness and etc. Information technology is only one stick of the wooden barrel. Unless it is the shortest stick that holds back the productivity, there is no urgent need to heavily invest on it, since investment on other resources such as a pleasant, comfortable and convenient working environment for staff to draw out their ideas right away. Without knowing the alternatives, invest in the most powerful information technology may be wasted.

Even if the information technology is the shortest bar of the barrel. It is too rushing to reach the conclusion that the most powerful advanced IT should be invested. Financially, investment requires the most important analysis-cost and benefit analysis. When it comes to cost and benefit, the investment cannot possibly get the same amount of benefit from every single additional dollar. Hence, is the best IT really necessary in terms of the benefits it can get? If the company spend 0.5 million on a up-to-date information technology and will get a yield of 1 million benefit in a long run, it sounds a wise investment. If to invest the best information technology costs 1 million, but the benefit it can bring is up to 1.1 million, then the yield of investment does not seem to pay back as well as the former plan.

The argument is based on an assumption that productivity needs to be improved. The fact that it is an advertising firm indicates that the products require innovation and creativity. To hire the right type of creative stuff may bring a far better result. The question is, does the productivity outweigh the innovation? Probably not. Hence, blindly improve the productivity of the company may not even suit the business plan of the company.

To sum it up, as the argument fails to consider possible options to improve employee productivity in order to choose the best driver to invest on, it precludes alternatives that may function better. Additionally, it ignores the marginal cost and effect of such investment. Moreover, it misses the feature and needs of the specific company in question, thus may cause overinvestment in non-core aspects of the company. With these reasons altogether, it is not hard to spot that the argument, though sounds logical from the first glimpse, is not truly convincing. Without further information on the alternatives evaluated and compared with such strategy, quantitative analysis of cost and benefits and more analysis on the company's current IT system, the argument will not take a firm stand.

想问问大家还有什么思路。

Dechu

数列，a_0=3， a_(n+1)=2*a_n -1 求a_20-a_19。 答案是2^19

个人意见:
   a_(n+1) = 2*a_n - 1
 等价:   a_(n+1) - 1 = 2 * (a_n - 1)
     设 b_n = a_n - 1   .............
     则 b_(n + 1) = 2 b_n
    因为 a_0 = 3
    所以 b_0 = a_0 -1  = 2^1
             b_1 = 2b_0   = 2^2
             b_2 = 2b_1   = 2^3
             ...
             b_n = 2^(n+1)
    因为 : a_n  = b_n + 1
    所以   a_20 - a_19 = 2^21 + 1 - 2^20 - 1
                                    = 2^20
请大牛 指正.

-- by 会员 samalex (2010/9/16 23:06:39)

我也觉得你这个答案对

-- by 会员 zetsubo (2010/9/16 23:22:40)

sorry，应该是a_1=3。我记得当时在考场上推出的是 a_n=2^n+1

Dechu

对了，我也每次是第一道题，非常非常的不确定！这是为什么呢？！导致后面的发挥非常的慌乱。

-- by 会员 BLinging (2010/9/16 22:35:44)

我当时的考前一分钟注意事项超时了，不知道有没有影响-_-

当时我还在带耳塞，记得剩下20多秒，一抬头发现题已经出来了。。

Dechu

第二题有点迷茫，既然有疗效的60%有副作用，那有副作用的不是必然少于有疗效的吗？

-- by 会员 zetsubo (2010/9/16 22:27:42)

我的理解是类似韦恩图那种题，有的人既有疗效也有副作用

Ivanka囡

最好能赶在圣诞节前夕把东西寄出去

samalex

数列，a_0=3， a_(n+1)=2*a_n -1 求a_20-a_19。 答案是2^19

个人意见:
   a_(n+1) = 2*a_n - 1
 等价:   a_(n+1) - 1 = 2 * (a_n - 1)
     设 b_n = a_n - 1   .............
     则 b_(n + 1) = 2 b_n
    因为 a_0 = 3
    所以 b_0 = a_0 -1  = 2^1
             b_1 = 2b_0   = 2^2
             b_2 = 2b_1   = 2^3
             ...
             b_n = 2^(n+1)
    因为 : a_n  = b_n + 1
    所以   a_20 - a_19 = 2^21 + 1 - 2^20 - 1
                                    = 2^20
请大牛 指正.

-- by 会员 samalex (2010/9/16 23:06:39)

我也觉得你这个答案对

-- by 会员 zetsubo (2010/9/16 23:22:40)

sorry，应该是a_1=3。我记得当时在考场上推出的是 a_n=2^n+1

-- by 会员 Dechu (2010/9/16 23:33:49)

那答案就是 2^19 啦, 谢谢LZ

wasbwsnm

第三题和第四题怎么解？
我第三题接出来是a(3+根2+根3).
第四题只知道m还是没办法阿？。。。平移了还是没解出来～～笨阿我～～