1) Given a four-digit odd number which is greater than 9 000 and is divisible by13
When rounded off to 3 signigicant figures. it is divisible by 4. When rounded off to 2 signigicant figures, it is divisible by 11. Find the number.
2) Is .√a^2 = a true for any value of a? Given an example to support your answer?
MATHS
2010-07-12 6:57 pm
回答 (2)
2010-07-12 8:48 pm
✔ 最佳答案
1)The number
= 9855 to 9864 , 9875 to 9884 , 9895 to 9904 , 9915 to 9924 or 9935 to 9944.
9855 = 13 x 758 + 1 , so 9855 to 9864 are rejected.
9875 = 13 x 759 + 8 , so the number can be 9875 + 13-8 = 9880.
9895 = 13 x 761 + 2 , so 9895 to 9904 are rejected.
9915 = 13 x 762 + 9 , so the number can be 9915 + 13-9 = 9919.
9935 = 13 x 764 + 3 , so 9935 to 9944 are rejected.
The number is 9880 or 9919.
2)
No.
When a is negative , for example a = - 2 ,
√a^2 = √(- 2)^2 = √4 = 2 is not = a = - 2.
2010-07-12 12:52:27 補充：
Some mistake , For 1) , odd number only = 9919. Sorry!!
2010-07-12 8:12 pm
你可唔可以用中文say?????
收錄日期: 2021-04-21 22:12:03
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100712000051KK00385