[原创] 十月七日机井 数学部分11道题

evaxiao

In which quadrants do the roots of the equation lie, given x and y are integers: Y = (x-2)^2 -1

这道题主要是题干是什么意思啊? roots of the equation lie,roots是指方程的解还是根啊?

benwinner456

11题应该是18小时，设小的2X小时，大的X小时。设速度的那位把小的速度设的大于大的，不对

15题：1+C(2,3)+C(1,3) +1=8

17题：9/12 + 12/20 =9/20

18题：选D,X+13的余数只为1，不能为6

benwinner456

不好意思，17题写错了，应该是

9/12*12/20=9/20

kevin5

以下是引用mecca7a在2006-10-8 15:45:00的发言：

14. 5 people are to be seated around a circular table. Two seating arrangements are considered different only when the positions of the people are different relative to each other. What is the total number of different possible seating arrangements for the group?

问一下这题的解法，谢谢！

我也请教14题的解法。

gogmat

18. What is the remainder when positive integer x is divided by 7

1). X+1 is divisible by 7

2). X+13 is divisible by 7

my explain:

1) x+1=7a, x=7a-1,余数为1

x+13=7a, x=7a-13, then 7a-14+1=7(a-2)+1, so remainder is 1,

1) and 2) are correct, answer is D

12. What is the total number of different 5-digit numbers that contain all of the digits 2, 3, 4, 7, and 9 and in which none of the odd digits occur next to each other?

my explain:

p(3,3)P(2,2)=12, 3个数排3个位置，2个数排2个位置，请指教？

13. One integer will be selected randomly from the integers 11 to 60, inclusive. What is the probability that the selected integer will be a perfect square or a perfect cube?

my explain:

总共60-11+1=50 个数可选，分母是50； 总共16，25，27，36，49 可能， 只可选这5个的任何一个，分子是5，5/50=1/10

20. K=wxyz, where w, x, y, z are prime numbers. Not including 1 and K, how many factors does K have?

My answer: 14

有谁能详细解释这道题吗？

jillgu

14. 5 people are to be seated around a circular table. Two seating arrangements are considered different only when the positions of the people are different relative to each other. What is the total number of different possible seating arrangements for the group?

答案是什么啊

gogmat

我蠢呀，才发现这贴已有5pages， 我看了1页就回帖，浪费大家的青春!sorry

Thank you for the 20T explaination.

simona

根出现在124象限，叫不叫能确定what quadrant exactly x and y lie

ldimple

以下是引用mecca7a在2006-10-8 16:22:00的发言：
已经看过了yaomao女侠的解法！

呵呵,我找到了....

[此贴子已经被作者于2006-10-10 4:21:34编辑过]

kangchia

20. K=wxyz, where w, x, y, z are prime numbers. Not including 1 and K, how many factors does K have?

My answer: 14

   factor 共有

    (1+1)(1+1)(1+1)(1+1)=16

Not including 1 and K

so  16-2=14

    (1+1)(1+1)(1+1)(1+1)=16

Not including 1 and K

so  16-2=14