{x+y-z=6,x-y+2z=-7,3x+2y+z=7解三元一次方程,
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{x+y-z=6,x-y+2z=-7,3x+2y+z=7解三元一次方程,
{x+y-z=6,x-y+2z=-7,3x+2y+z=7解三元一次方程,
{x+y-z=6,x-y+2z=-7,3x+2y+z=7解三元一次方程,
x+y-z=6 (1)
x-y+2z=-7 (2)
3x+2y+z=7 (3)
分析:利用加减消去法,将未知数逐一消去
(1) + (2):2x + z = -1 (3) (消去y)
(1)*2:2x + 2y - 2z = 12 (4)
(3) - (4):x + 3z = -5 (5) (消去y)
(5)*2:2x + 6z = -10 (6)
(6) - (3):5z = -9 (消去x)
z = -9/5
将 z = -9/5 代入 (3)式:得 2x + (-9/5) = -1
2x = 4/5
x = 2/5
将 x = 2/5,z = -9/5,代入 (1)式:得 2/5 + y - (-9/5) = 6
y = 19/5
所以答案为 x = 2/5,y = 19/5,z = -9/5 (经验算,准确无误)
若X:Y:Z=5:6:7那么(Y-X):(Y+Z)和(X+2Y+3Z):(3X+2Y+Z)
x+y+z=6 x+2y+3z=14 y+1=z
(1)X+Y=15,Y+Z=-6,Z+X=7.(2)X+Y=-14,Y+Z=-7,Z+X=9.(3)X+Y=0,Y+Z=-1,Z+X=-1.
已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z
试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y)
2x-3y-z=-6 7x-y+2z=-17 x-y+z=-6
2x+5y+4z=6,3x+y-7z=-4,x+y-z=?
已知2x+5y+4z=6 3x+y-7z=-4求x+y-z
5x+3y+2z=2011 4x+6y+7z=2012 求x+y+z
1.{x:y:z=3:4:5 2x+3y-5z=-142.{x-y-z=-1 3x+5y+7z=11 4x-y+2z=-13.{x+y=1 x+z=0 2x+y+2z=44.{x-y+z=-3 2x-y-z=-2 -3x+y+z=-15.{x-y+z=-3 3x+y-4z=6 2x+y-z=36.{x-2y+5z=16 2x+y-5z=7 2x-y+z=38
解三元一次方程组 ①2x-y+z=1 3x+y -2z=2 X+2y-z=3 ②x-4y+z=-3 2x+Y-Z=18 X-Y-Z=7 ③4x+4y+2z=7 6X-4y-z=6 2x-y+z=1
6x+3y-2z=108,9x+7y-3z=212,3x-2y+5z=38,求x,y,z
若4x-3y-6z=0,x+2y-7z=0,则x+y+z/3x-y+z=?
已知4x-3y-6z=0,x+2y-7z=0,求5x+2y-z/2x-3y-10z
已知:4x-3y-6z=0,x+2y-7z=0.求出x-y+z÷x+y+z=?
已知4x-3y-6z=0,x+2y-7z=0,则x-y+z/x+y+z=_________
已知4x-3y+6z=0 x+2y-7z=0 则x-y+z/x+y-z=?
4x-3y-6z=0,x+2y-7z=0,x-y+z/x+y+z=?