一條二元一次方程問題
2007-02-16 7:46 pm
The sum of the digits of a three-digit number is 13. The hundreds digit is smaller than twice the tens digit by 2. If we exchange the positions of the hundreds digit and the units sigit, the number obtained is smaller than the original number by 297. Find the original three-digit number.
回答 (2)
2007-02-16 7:56 pm
✔ 最佳答案
let the original number is abca+b+c=13.......formula 1
2b-2=a
b=(2+a)/2.....formula 2
99a-99c=297
a-c=3
c=a-3.....formula 3
sub formula 3 and formula 2 to formula 1......a+(2+a)/2+a-3=13
2.5a-2=13
a=15/2.5=6
b=(2+a)/2 so b=4
c=a-3 so c=3
so let the original number is 643
2007-02-16 12:10:54 補充：
i think it is not proper to use 2 formula to calculate because there are 3 conditions gave and we must use 3 unknown for the first condition.
2007-02-16 7:51 pm
The three digit number is XXX plz use your brain to think it so easy
收錄日期: 2021-04-13 14:53:35
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070216000051KK01246