1. A two-digit positive number is decreased by 27 when its digits are reversed. The product of the two digits is 10. Find the number.
2. Solve the equation log(base2)(x+1)=5.
2條S.4 maths~~!!
2014-04-21 6:16 am
回答 (1)
2014-04-21 7:32 am
✔ 最佳答案
Let the two-digit positive number is xy(10x + y) - (10y + x) = 27...(1)
xy = 10...(2)
From (1), 10(x - y) + (y - x) = 27
x - y = 3 or x = y + 3
Sub. into (2) y(y + 3) = 10 => y = 2
Then x = 5 and the number is 52
(2) log_2 (x + 1) = 5
2^5 = x + 1
32 = x + 1
x = 31
收錄日期: 2021-04-24 23:24:36
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https://hk.answers.yahoo.com/question/index?qid=20140420000051KK00145