请教几个数学题，请指教

lujiamu

请教高人10个数学题，望指教：
1.    If an integer n is to be chosen at random from the integers 1 to 96, inclusive, what is the probability that n(n+1)(n+2) will be divisible by 8? 请指教解题过程、答案以及考点，先谢谢谢谢了。

2.    99999^2-1^2=？
A 10^10-2 b (10^5-2)^2 c 10^4(10^5-2) d 10^5(10^4-2) e 10^5(10^4-2)

3.    Which of the following is equal to (2^k)5^k-1)?
A 2(10^k-1) b 5(10^k-1) c 10^k d 2(10^k) e 10^2k-1

4.    If “根号下”x=25, then x^3-x^2=?

5.    What is the value of (x-y)^4
1.    The product of x and y is 7.
2.    X and y are integers.

6.    In the decimal representation of x, where 0<x<1, is the tenth digit nonzero?
1.    16x is an integer.
2.    8x is an integer.

7.    What is the remainder when the positive integer x is divided by 8?
1.    When x is divided by 12, the remainder is 5.
2.    When x is divided by 18, the remainder is 11.

8.    If x,y and k are positive number such that (x/x+y)(10)+(y/x+y)(20)=k and if x<y, which of the following could be the value of k?
10,12,15,18,30

9.    A shipment of 8 television sets contains 2 black-and-white sets and 6 color sets, if 2 television sets are to be chosen at random from this shipment, what is the probability that at least 1 of the 2 sets chosen will be a black and white set? 概率，烦请列出公式。

10.    In a certain game player with red card and blue card, each red card has a point value of x and each blue has a point value of y, wherex>y and x and y are positive integers. If a player has 5 red card and 3 blue cards, what is the average point value of the 8 cards that the player has?
1.    The average point value of one red and one blue card is 5.
2.    The average point value of the 8 cards that the players has is an integer.

flyst7

1.不知道我的方法麻烦不
n(n+1)(n+2)有两汇种情况
a. 奇偶奇 偶数n+1必然是8的倍数  n+1 是大于等于2 小于等于97的正整数 所以有8-96中 12个 所以n有12个成立
b. 偶奇偶 两个偶数必然一个只是2的倍数一个是4的倍数 所以N只要是偶数就行有1-96中48个

所以一共有60种情况 概率是60/96= 5/8 有点虚 不知道有这选项没=。=

2.平方差呀  99999^2-1^2=（99999+1）（99999-1）=100000×（100000-2）=10^5(10^5-2)

你DE选项应该是有一个错了吧

3.题目括号混乱啊 是不是(2^k)5^(k-1)?

如果是的话 (2^k)5^(k-1)=2[2^(k-1)][5^(k-1)]=2[10^(k-1)]

4.x^(1/2)=25  x=625

 x^3-x^2=x^2(x-1)=625*625*624

5. C吧 X*Y=7 XY都是整数 X=1 Y=7 or X=7 Y=1 结果都一样

lujiamu

谢谢了啊!!!!