先說抱歉 因為不會做的題目實在很多...
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 請問這怎麼求出來的？
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?
(多選) A. 200 B. 2*C(5,2)*C(5,3) C. 100 D. C(5,2)*C(5,3) E. C(10,5)
我是想說有兩種情況：
(情況一) 紅2藍3 所以C(5,2)*C(5,3)
(情況二) 藍2紅3 所以也是C(5,2)*C(5,3)
然後相乘得100 所以答案是C跟Ｄ, 但是答案卻是A跟Ｂ...
請問我是哪邊出錯呢？
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!...可能是我理解題目有誤...
4. If 3^6x=8,100, what is the value of (3^x-1)^3? (單選) 答案是D 請問怎做？
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? (單選) 答案是E 這題也是想知道要怎麼做
A. 1 B. 2 C. 4 D. 6 E. 8
看來我好像關於指數那部分很糟糕啊XDD
然後不排除答案有誤...因為是補習班習題 只有題目跟解答 沒有解題說明