3x+4y=160
4y+2z=190
3x+2z=140
識計?
唔識解聯立方程
2010-01-07 5:51 am
回答 (2)
2010-01-07 5:55 am
✔ 最佳答案
3x+4y=160 ... (1)
4y+2z=190 ... (2)
3x+2z=140 ... (3)
(2) - (1) => 2z - 3x = 30 ... (4)
(3) + (4) => 4z = 170
z = 85/2
Sub into (3), 3x + 2(42.5) = 140
x = 55/3
Sub into(1), 55 + 4y = 160
y = 105/4
2010-01-07 6:23 am
3x+4y=160 ... (1)
4y+2z=190 ... (2)
3x+2z=140 ... (3)
(2) - (1) , 2z - 3x = 30 ... (4)
(3) + (4), 4z = 170
.'.z = 85/2
Sub z = 85/2 into (2), 4y + 2(85/2) = 190 .'. y= 105/4
Sub into(1), 3x + 4(105/4) = 160
.'.x=55/3
4y+2z=190 ... (2)
3x+2z=140 ... (3)
(2) - (1) , 2z - 3x = 30 ... (4)
(3) + (4), 4z = 170
.'.z = 85/2
Sub z = 85/2 into (2), 4y + 2(85/2) = 190 .'. y= 105/4
Sub into(1), 3x + 4(105/4) = 160
.'.x=55/3
收錄日期: 2021-04-23 23:23:08
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https://hk.answers.yahoo.com/question/index?qid=20100106000051KK01708