一隻馬在沙漠走失了5天。第一天，牠不知走了多少公里;之後，牠每天都比前一天多走一公里，到了第5天牠成功走出沙漠，牠在沙漠共走了55公里。問這匹馬在最後一天走了多少公里﹖?
回答 (2)
2017-04-09 5:07 pm
✔ 最佳答案
Sol設第一天走了x公里
(x+x+4)*5/2=55
(2x+4)*(5/2)=55
(x+2)*5=55
x+2=11
x=9
2017-04-09 6:16 pm
Let the first day = X 公里
The second day = X+1 公里
The third day = X+2 公里
The 4th day = X+3 公里
The 5th day = X+4 公里
X+(X+1)+(X+2)+(X+3)+(X+4)=55
5X + 10 = 55
5X = 55 - 10
5X = 45
X = 9
because 5th day(the last day) = X+4
when X = 9
5th day = 9+4
5th day = 13公里
The second day = X+1 公里
The third day = X+2 公里
The 4th day = X+3 公里
The 5th day = X+4 公里
X+(X+1)+(X+2)+(X+3)+(X+4)=55
5X + 10 = 55
5X = 55 - 10
5X = 45
X = 9
because 5th day(the last day) = X+4
when X = 9
5th day = 9+4
5th day = 13公里
收錄日期: 2021-04-18 16:11:18
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20170409080327AAvQCXD