Question

解方程三元一次方程 2x＋3y＋z＝6 x－y＋2z＝－1 x＋2y－z＝5

Answer 1

2x＋3y＋z＝6 (1)
x-y＋2z＝-1 (2)
x＋2y－z＝5 (3)

(3)-(2)
3y-3z = 6
y-z = 2 (4)

2(3)-(1)
y-3z=4 (5)

(4)-(5)
2z=-2
z=-1

from (4)
y+1=2
y=1

from (3)
x＋2 +1＝5
x=2

(x,y,z)=(2,1,-1)

Answer 2

x=2 y=1 z=-1

Answer 3

2x+3y+z=6(1)
x-y+2z=-1(2)
x+2y-z=5(3)
消x,(2)x2 2x-2y+4z=-2(4)
(1)-(4) 5y-3z=8(5)
(3)-(2) 3y-3z=6 y-z=2(6)
y=2+z(7)
把（7）代入（5） 5（2+z)-3z=8
10+5z-3z=8
2z=-2
z=-1
y=2-1=1
x=5-2y+z=5-2-1=3-1=2
x=2
y=1
z=-1

Answer 4