推 redeyes:非常感謝!! 09/02 00:20
※ 引述《redeyes (NimmDeineHoeflichkeit)》之銘言：
: 29. The annual rent collected by a coporation from a certain building was x
: percent more in 1998 than in 1997 and y percent less in 1999 than in 1998. Was
: the annual rent collected by the coporation from the building more in 1999 than
: in 1997?
: (1) x>y
: (2) (xy)/100<x-y
: 答案是B
: 請問式子是怎麼導出來的呢
設1997年為1
1998：1+x%
1999：(1+x%)(1-y%)
依題意，要判定(1+x%)(1-y%)>1是否成立
上式展開得1+x%-y%-xy%%>1
左右移項得x%-y%>xy%%
兩邊同乘100得x-y>xy%，也就是條件二給的式子
故條件二單獨即成立，答案B
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