{y=2x-1,2x+3y+z=8,3x+2z=-4解下列方程组
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{y=2x-1,2x+3y+z=8,3x+2z=-4解下列方程组
{y=2x-1,2x+3y+z=8,3x+2z=-4
解下列方程组
{y=2x-1,2x+3y+z=8,3x+2z=-4解下列方程组
(1){y=2x-1,①
2x+3y+z=8,②
3x+2z=-4③
②×2-③,得
x+6y=20④
①代入④,得
x+12x-6=20
13x=26
x=2代入④,得
2+6y=20
y=3
所以
z=8-2x-3y=8-2×2-3×3=-5
即
x=2
y=3
z=-5
y=2x-1 (1)
2x+3y+z=8 (2)
3x+2z=-4 (3)
由(3)得z=-2 -(3/2)x
y=2x-1 z=2-(3/2)x代入(2)
2x+3(2x-1)+[2-(3/2)x]=8
整理,得
13x=9
x=9/13
y=2x-1=18/13-1=5/13
z=2- (3/2)x=2-(3/2)(9/13)=25/26
x=9/13 y=5/13 z=25/26
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{x+y+z=1 x-2y+3z=5 2x-3y-3z=-8
{x+2y+z=8{2x-y-z=-3{3x+y-2z=-1
{x+2y+z=8,2x-y-z=-3,3x+y-2z=-1
x+y+z=-1 4x-2y+3z=5 y-z=8-2x
2x+3y+z=8 4x-y-z=10 x+2y-z=1
{x+y+z=1 {x+3y+7z=-1 {x+5y+8z=2
X/10=Y/8=Z/9,则X+Y+Z/2Y-3Z
x+y+z=6 x+2y+3z=14 y+1=z
{x+y+z=1;x+3y+7z=-1;z+5y+8z=-2