Mrs chan wants to spend $ 25 to buy some orange and apples . lf she buys 2
apples and 8 oranges , she will have $ 1 left . lf she buys 8 apples and 4
oranges , she will be short of $ 1 . What are the prices of an apple and an
orange ?
二元一次方程
2008-03-07 5:31 am
回答 (3)
2008-03-07 5:40 am
設每個蘋果＄ｘ；每個橙＄ｙ
25-2x-8y=1 －１
25-8x-4y=-1－２
２x2
50-16x-8y=-2 －３
３－１
25-14x=-3
28=14x
x=2
代x=2入２
25-8(2)-4y=-1
10=4y
y=2.5
所以每個蘋果＄2；每個橙＄2.5
25-2x-8y=1 －１
25-8x-4y=-1－２
２x2
50-16x-8y=-2 －３
３－１
25-14x=-3
28=14x
x=2
代x=2入２
25-8(2)-4y=-1
10=4y
y=2.5
所以每個蘋果＄2；每個橙＄2.5
2008-03-07 5:40 am
Let the price of apple=$x,
the price of orange=$y,
25-2x-8y=1---(1)
25-8x-4y=-1---(2)
(2)*2:
50-16x-8y=-2---(3)
(1)-(3):
-25+14x=3
x=2
put x=2 into (1):
25-2(2)-8y=1
y=2.5
the price of orange=$y,
25-2x-8y=1---(1)
25-8x-4y=-1---(2)
(2)*2:
50-16x-8y=-2---(3)
(1)-(3):
-25+14x=3
x=2
put x=2 into (1):
25-2(2)-8y=1
y=2.5
2008-03-07 5:39 am
Let Appble be "x" and orange be "y"
2x + 8y = 25-1 ................................(1)
8x + 4y = 25+1 ................................(2)
then (2) x 2
2x + 8y = 24 ....................................(1)
2(8x + 4y) = 26 x 2 ..........................(2)
then (2) - (1)
14x = 28
x = 2
then use (1)
2(2) + 8y = 24
4 + 8y = 24
8y = 20
y = 2.5
2x + 8y = 25-1 ................................(1)
8x + 4y = 25+1 ................................(2)
then (2) x 2
2x + 8y = 24 ....................................(1)
2(8x + 4y) = 26 x 2 ..........................(2)
then (2) - (1)
14x = 28
x = 2
then use (1)
2(2) + 8y = 24
4 + 8y = 24
8y = 20
y = 2.5
收錄日期: 2021-04-14 20:19:58
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080306000051KK02751