解聯立二元一次方程 (要完整的) 2x+3y=7 3x-4y=2?

2017-01-15 11:46 pm

回答 (8)

2017-01-16 11:28 am
✔ 最佳答案
As per attached sheet
2017-03-16 8:07 pm
2x+3y=7-------(1)
3x-4y=2--------(2)
(1)*3
6x+9y=21
(2)*2
6x-8y=4
(1)-(2)
9y+8y=21-4
17y=17
y=1
y=1 入(2)
3x-4(1)=2
3x=6
x=2
把y=1帶入得x=2
2017-02-18 11:29 pm
2X+3y= 7
3X-4y= 2

14= 4x+6y=21x-28y
21x-28y = 4x+6y
21x-4x=6y+28y
17x=34y
1x=2y

2(2y)+3y=7
4y+3y =7
7y=7
y=1


1x= 2y
y=1 x=2
2017-02-04 9:18 am
2x+3y=7 (1)
3x-4y=2 (2)
(1)x3:
6x+9y=21 (3)
(2)x2:
6x-8y=4 (4)
(4)-(3):
6x-8y-6x-9y=21-4
-17y=17
y=-1
Put y=-1 into (1)
2x+3(-1)=7
2x-3=7
2x=10
x=5
2017-01-31 1:52 am
2x+3y=7 →乘3→6x+9y=21--⓵
3x-4y=2→乘2→6x-8y=4--⓶
⓵-⓶
→17y=17
→y=1
→x=2
2017-01-26 2:18 am
把2x+3y=7乘以3變成6x+9y=21
把3x-4y=2乘以2變成6x-8y=4
兩式相減得17y=17,y=1
把y=1帶入得x=2
2017-01-16 12:04 am
X = 2
Y = 1

2x2+3x1=7
3x2-4x1=2
2017-01-16 12:00 am
3x-4y=2
2x+3y=7
相減得
x-7y= -5
再乘二得
2x-14y=-10
再跟
2x+3y=7
相減得
17y=17
y=1
x=2


收錄日期: 2021-04-18 15:58:34
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20170115154645AAUE8MA

檢視 Wayback Machine 備份