一道GRE数学In a list of numbers,the first number is 3,the second is 4,and each subsequent number is the sum of all the proceeding numbers in the list.If the 20th number in the list is x,what is the 25th number in the list?A 7x B 16x C 32x D 35x E

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一道GRE数学In a list of numbers,the first number is 3,the second is 4,and each subsequent number is the sum of all the proceeding numbers in the list.If the 20th number in the list is x,what is the 25th number in the list?A 7x B 16x C 32x D 35x E
一道GRE数学
In a list of numbers,the first number is 3,the second is 4,and each subsequent number is the sum of all the proceeding numbers in the list.If the 20th number in the list is x,what is the 25th number in the list?A 7x B 16x C 32x D 35x E 161x
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选C，理由如下。
The proceeding number in the list are as follows.
1. 3
2. 4
3. 3+4=7
4. 7+7=14
5. 7+7+7*2=7*4=28
6. 7+7+7*2+7*4=7*8=56
.......
Above a regulation could be ...

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选C，理由如下。
The proceeding number in the list are as follows.
1. 3
2. 4
3. 3+4=7
4. 7+7=14
5. 7+7+7*2=7*4=28
6. 7+7+7*2+7*4=7*8=56
.......
Above a regulation could be find that the n th number equals to 7*(2^(n-3))
So the 20th number is 7*(2^17).
The 25th number is 7*(2^22), which is 2^5=32 times as much as the 20th number.
Choose C.

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1.先看一下前6个数吧，分别是3,4,7,14,28,56...所以在第3为以后，你会发现下一个数就是上一个数的2倍；
2.知道这个规律后，来看一下第20到25个数：x,2x,4x,8x,16x,32x所以你看到了，第25个数就是32x，就是答案C。
希望对你有帮助啊！！！

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题目翻译：在一个数列中，第一个数字为3，第2个数字为4，以后每个数字都输它前面数字的综合，如果数列中第20个数是X，那么第25个数是多少？
思路：不必管X具体是多少，只需要关注题目中“each subsequent number is the sum of all the proceeding numbers in the list”
把前19个数的和看做一个整体
因为第20个数是\x09X，所以，前19个数的和也为X，以此类推
则第21个数为X+X=2X（前20个数的和为2X）
则第22个数为2X+2X=4X（前21个数的和为4X）
则第23个数为4X+4X=8X（前22个数的和为8X）
则第24个数为8X+8X=16X（前23个数的和为16X）
则第25个数为16X+16X=32X
所以答案选C

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一道GRE数学In a list of numbers,the first number is 3,the second is 4,and each subsequent number is the sum of all the proceeding numbers in the list.If the 20th number in the list is x,what is the 25th number in the list?A 7x B 16x C 32x D 35x E the weight of that GRE数学题中boxplots/box-and-whisker the number of times a value appears in the list is called the weight of that value. m_____a list of dishes in a esp.in a restaurant 一道GRE数学题,A certain identification is a list of five symbolsA certain identification is a list of five symbols:S1,S2,D1,D2,D3,Each of the first 2 symbols must be one of the 26 letters of the English alphabet,and each of the last 3 symbols mu 2 standard deviation（sd）是2倍sd的意思吗,可以这样省略比较级?A list of numbers has a mean of a standard deviation of 2.5.If x is a number in the list that is 2 standard deviations above the mean,what is the value of 这是新GRE官这是一道完形填空,Every year,the people in charge of the Rebecca Caudil Youth Reader’s book award publish a list of books that students will vote on and declare as the best in the list GRE 数学一道机经 a list a list of see off in spite of帮...解决困难一点也不.从某种程度上讲...属于 SAT数学真题The least and greatest numbers in a list of 7real numbers are 2 and 20,respectively.The median of the list is 6,and thenumber 3 occurs most often in the list.Which of the following could be theaverage (arithmetic mean) of the numbers i a list of things是什么意思 single article in a list 一道gre数学题目A rhombus has a base of 10 and a height of 4the area of the rhombus的数值大还是the perimeter of the rhombus的数值大,谢谢,我不知道怎么算也英语作文!think of favourute food in hometown.make a list of ingredients Make a list of the things you like in a sandwich. 怎么分析这句话? Make a list ___________food to buy.A.in B.at C.of D.for make a list of requirements needed for a high school graduate in America college A list of food in a restaurant.猜一个以m开头的英文单词一道英语单选题求解!If you have a lot of things to do,just make a list and ___them in order of importaneA.analyse B.examine C.arrange D.construce