利用代入消元法解下列聯立二元一次方程式。(要步驟)
1 .x + y + 2 = 9x - 2y = 5
2.
╭ 2x - 5y = 7
｜
╰ 4x + 3y = 1
3.
╭ x + y = 2
｜
╰ x y
－ - － = 1
2 3
中三數,三條!
2007-10-06 7:53 pm
回答 (1)
2007-10-06 8:06 pm
✔ 最佳答案
1:x+y+2=5
x=5-2-y
x=3-y
9x-2y=5
9(3-y)-2y=5
27-9y-2y=5
-7y=5-27
y=-22/-7
y=22/7
x=3-y
x=3-22/7
x=-1/7
2:
2x-5y=7
2x=7+5y
x=(7+5y)/2
4x+3y=1
4(7+5y)/2+3y=1
14+10y+3y=1
13y=1-14
13y=-13
y=-1
x=(7+5y)/2
x=(7-5)/2
x=1
3:
x+y=2
x=2-y
x/2-y/3=1
(3x-2y)/6=1
3x-2y=6
3(2-y)-2y=6
6-3y-2y=6
y=0
x=2-y
x=2
收錄日期: 2021-04-13 13:47:36
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20071006000051KK01523