System of equations

2012-02-14 6:14 am
Solve the following equations :
x - 2y + 3z = 0 and
2x + 5y + 6z = 0.

回答 (2)

2012-02-14 7:37 am
✔ 最佳答案
x -2y + 3z = 0 ......[1]
2x+ 5y + 6z = 0...... [2]

[1] * 2 :
2x -4y + 6z = 0 ...... [3]

[2] - [3] :
9y = 0
y = 0

Put y = 0 into [1] :
x - 0 + 3z = 0
x = -3z
x/z = -3


Hence, y = 0 and x : z = -3 : 1

(To solve for 3 unknowns, there must be at least 3 equation.)
(There are only 2 equations, and thus the exact solutions of x an z cannot befound.)
參考: micatkie
2012-02-15 4:27 am
Actually x : z = -3 : 1 can be further expressed to give x = -3t and z = t : t∈R


收錄日期: 2021-04-13 18:32:23
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20120213000051KK00904

檢視 Wayback Machine 備份