Question

解三元一次方程组,方程组1：方程组2：X-2Y=-9 3X-Y+Z=4Y-Z=3 2X+3Y-Z=122Z+X=47；

Answer 1

X-2Y=-9 (1)

Y-Z=3 (2)

2Z+X=47 (3)

(3)-(1)

2Z+X-X+2Y=47+9

2Z+2Y=56

Y+Z=28 (4)

(2)+(4)

2Y=51

Y=51/2

Z=Y-3=45/2

X=2Y-9=42

3X-Y+Z=4 (1)

2X+3Y-Z=12 (2)

X+Y+Z=6 (3)

(1)+(2)

5X-2Y=16 (4)

(2)+(3)

3X+4Y=18 (5)

(4)×2+(5)

10X+3X=32+18

X=50/13

代入(4)

250/13-2Y=16

Y=21/13

Z=6-X-Y=7/13

所以X=50/13,Y=21/13,Z=7/13