推 ck901372:thx 09/22 21:30
※ 引述《ck901372 (孫臏)》之銘言：
: A store currently charges the same price for each towel that it sells. If the
: current price of each towel were to be increased by $1, 10 fewer of the
: towels could be bought for $120, excluding sales tax. What is the current
: price of each towel?
: Ans. $3
: 我從網路上找的解答:
: current price-x
: current quantity-y
: x*y=120
: current price increased by 1 =(x+1)
: current quantity decreased by 10=(y-10)
: (x+1)*(y-10)=120
: solving two equations
: x^2+x-12=0
: x=3
: GRE版有人討論這題
: 也沒有下文
: 想請問高手這題
: xy=120及(x+1)*(y-10)=120 如何從題目中看出
價格x數量＝120 價格加一塊的話 同樣的價錢少買十個
也就是(價格+1)x(數量-10)=120
兩個未知數可以由兩個方程式求解。
Dustin
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