方程式...急!!!
2007-08-12 11:11 pm
錢包內有$10和$5兩種硬幣，其中$5硬幣的數目較$10的5倍少3枚。若$5硬幣的總值較$10硬幣的總值多$150，求錢包內$10硬幣的總值。(必須使用方程式)
回答 (3)
2007-08-12 11:16 pm
✔ 最佳答案
設有$10硬幣 x 枚。則有$5硬幣(5x - 3)枚。
5元硬幣的總值
= 5(5x - 3)
= $(25x - 15)
10元硬幣的總值
= $10x
所以，
25x - 15 = 10x + 150
15x = 165
x = 11
所以，有$10硬幣11枚。
參考: Myself~~~
2007-08-12 11:58 pm
設10硬幣的總值是y(x=乘)
(5x10y-『3x10』x5)-10y=150
( 50y-150)-10y=150
50y+150-10y=150
40y+150=150
40y=0
y=0
10硬幣的總值是０.
(5x10y-『3x10』x5)-10y=150
( 50y-150)-10y=150
50y+150-10y=150
40y+150=150
40y=0
y=0
10硬幣的總值是０.
2007-08-12 11:21 pm
let $5 = X , $10 = Y
X= 3Y - - - -- - (1)
X-Y = 150 - - - - - -(2)
from (2):
X=150+Y - - - - - - - (3)
put (3) into (1)
150 + Y = 3Y
150 = 3Y - Y
150 = 2Y
75 = Y
X= 3Y - - - -- - (1)
X-Y = 150 - - - - - -(2)
from (2):
X=150+Y - - - - - - - (3)
put (3) into (1)
150 + Y = 3Y
150 = 3Y - Y
150 = 2Y
75 = Y
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070812000051KK02527