先说抱歉 因为不会做的题目实在很多...
1. After the decimal point is moved to its right six spaces, the positive
decimal x will then be nine times the reciprocal of the original decimal x.
What is the original decimal x? (填充) 答案:0.003 请问这怎么求出来的？
2. A bag contains 5 red balls and 5 blue balls. In how many ways can 5 balls
be drawn at random such that there are at least two balls of each colour?
(多选) A. 200 B. 2*C(5,2)*C(5,3) C. 100 D. C(5,2)*C(5,3) E. C(10,5)
我是想说有两种情况：
(情况一) 红2蓝3 所以C(5,2)*C(5,3)
(情况二) 蓝2红3 所以也是C(5,2)*C(5,3)
然后相乘得100 所以答案是C跟Ｄ, 但是答案却是A跟Ｂ...
请问我是哪边出错呢？
3. How many different 6-letters sequences are there that consist of 1 A,
2 B's, and 3 C's? (填充) 答案:60
可是我是算6!...可能是我理解题目有误...
4. If 3^6x=8,100, what is the value of (3^x-1)^3? (单选) 答案是D 请问怎做？
A.90 B.30 C.10 D.10/3 E.10/9
5. If n is a positive number, what is the remainder when (7^4n+3)(6^n) is
divided by 10? (单选) 答案是E 这题也是想知道要怎么做
A. 1 B. 2 C. 4 D. 6 E. 8
看来我好像关于指数那部分很糟糕啊XDD
然后不排除答案有误...因为是补习班习题 只有题目跟解答 没有解题说明