3(x+y)-4(x-y)=4 x+2y+3z=5

问题描述:

3(x+y)-4(x-y)=4 x+2y+3z=5
x+y/2+x-y/6=1 2x+3y+6z=9
5x+3y+9z=15
3(x+y)-4(x-y)=4 x+2y+3z=5 两式一道!(二元一次方程组)
x+y/2+x-y/6=1 2x+3y+6z=9 5x+3y+9z=15 (三元一次方程组)

3(x+y)-4(x-y)=4x+2y+3z=5 .1
x+y/2+x-y/6=1 2x+3y+6z=9 .2
5x+3y+9z=15 .3
1式*2-2式得:6X+Y=1
1式+2式-3式得:X+2Y=-1
3式-2式得:X+Z=2
6X+Y=1
X+2Y=-1
X+Z=2
X=3/11.
Y=-7/11
Z=19/11