三元一次方程组怎麼解啊?3x-y+z=4①2x+3y-z=12②x+y+z=6③
2019-05-07
三元一次方程组怎麼解啊?
3x-y+z=4①
2x+3y-z=12②
x+y+z=6③
优质解答
3x - y + z = 4 ①
2x + 3y - z = 12 ②
x + y + z = 6 ③
①+② 得
5x + 2y = 16
y = 8 - 5x/2
①+③ 得
4x + 2z = 10
z = 5 - 2x
由③得,
x + 8 - 5x/2 + 5 - 2x = 6
2x + 16 - 5x + 10 - 4x = 12
7x = 14
x = 2
y = 3
z = 1
3x - y + z = 4 ①
2x + 3y - z = 12 ②
x + y + z = 6 ③
①+② 得
5x + 2y = 16
y = 8 - 5x/2
①+③ 得
4x + 2z = 10
z = 5 - 2x
由③得,
x + 8 - 5x/2 + 5 - 2x = 6
2x + 16 - 5x + 10 - 4x = 12
7x = 14
x = 2
y = 3
z = 1