f4 maths!!!!!!!!!!PLZ HELP!
2007-09-23 5:54 am
A housewife pays $75 for some apples. If the price of each apple is reduced by $0.5 ,she can buy 5 more apples with the same amount od money.Find the original price of an apple.
回答 (2)
2007-09-23 6:10 am
✔ 最佳答案
let x=no.of apple y=price of one applexy=75 ...(1)
y=75/x...(2)
75= (x + 5)(y - 0.5)
75= xy + 5y - 0.5x - 2.5
75= 75 + 5(75/x) - 0.5x -2.5 (sub 1and 2 )
0.5x^2 + 2.5x - 375=0
x^2 + 5x -750 =0
(x+30)(x-25)
x=25 or -30(rej)
y=75/x
y=3
so~the original price of an apple =$3
參考: 自己
2007-09-23 6:13 am
Let $x be the original price of an apple
75/(x-0.5) - 75/x = 5
(75x - 75(x-0.5)) /x(x-0.5) = 5
75x -75x +37.5 = 5(x^2-0.5x)
5x^2 -2.5x-37.5= 0
(x-3)(x+2.5)= 0
x = 3 or x = -2.5
∵The price must be positive
∴The original price of an apple is $3
75/(x-0.5) - 75/x = 5
(75x - 75(x-0.5)) /x(x-0.5) = 5
75x -75x +37.5 = 5(x^2-0.5x)
5x^2 -2.5x-37.5= 0
(x-3)(x+2.5)= 0
x = 3 or x = -2.5
∵The price must be positive
∴The original price of an apple is $3
參考: 自己
收錄日期: 2021-05-03 07:06:12
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070922000051KK05034