1) 3^2005(-1/3)^2008=?
2) (5x-y)^2-17(x^2)-13(y^2)=?
3) There are some drinks in the refrigerator,10 of them are orange juice.If a drink is taken at random,the probability of taking a orange juice is 5/11.What is the total no. of drinks in the refrigerator??
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2008-08-08 1:17 am
回答 (1)
2008-08-08 1:41 am
✔ 最佳答案
1.3^2005(-1/3)^2008 = 3^2005(-1)^2008/3^2008 = 3^(2005 - 2008)= 3^(-3) = 1/27.
2.
(5x-y)^2 - 17x^2 - 13y^2 = 25x^2 + y^2 - 10xy - 17x^2 - 13y^2
= 8x^2 - 10xy - 12y^2 = 2(4x^2 - 5xy - 6y^2) = 2(4x + 3y)(x- 2y).
3.
Let total no. of drinks = n.
10/n = 5/11, therefore, n = 22.
2008-08-07 17:43:56 補充：
For Q1, (-1)^2008 = 1.
收錄日期: 2021-04-25 22:37:26
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https://hk.answers.yahoo.com/question/index?qid=20080807000051KK02158