simultaneous equation
2008-12-26 5:45 am
the sum of the two digits of a two-digit number is 9. If the digits are reversed, the number will be increased by 45. find the original number
回答 (2)
2008-12-26 6:05 am
✔ 最佳答案
Let a and b be the tens digit and the unit digit respectively.
a + b = 9 ...... (1)
(10b + a) - (10a + b) = 45 ...... (2)
(2):
10b + a - 10a - b = 45
-9a + 9b = 45
-a + b = 5 ...... (3)
(1)+(3):
2b = 14
b = 7
Put b = 7 into (1):
a + (7) = 9
a = 2
Ans: The original number is 27.
=
2008-12-26 6:39 am
收錄日期: 2021-04-25 14:33:40
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20081225000051KK01614