[問題]PRep裡的DS,請教一下~

[balanana]

In a certain conference room each row of chairs has the same number of chaires, and the number of rows is 1 less than the number of the chair in a row. how many chaire are in a row?
1.there is a total of 72 chairs.
2. after 1 chair removed form the last row, there is a total of 17 chairs in the last 2 rows.

ans: D

我連題目都看不太懂~
不知道這題目到底在講啥耶@@

[yuerwu]

在說，有一個房間裡面放了椅子，
每一排有K張椅子，然後有(k-1)排，問你說，總共有多少椅子呢？
也就是要求k(k-1)

1. 總共有72張椅子。可列示為k^2-k-72=0 只有唯一正數解。
2. 當一張椅子移開以後，最後兩排的椅子數變成17
所以也可以知道，原來的時候，一排有(17+1)/2=9張椅子喔。

[balanana]

太感謝了~我真的題目看不太懂說~謝謝尼的解釋:D