3X+2Y+Z=13,X+Y+2Z=7,2X+3Y-Z=12 最好先消去什么
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3X+2Y+Z=13,X+Y+2Z=7,2X+3Y-Z=12最好先消去什么3X+2Y+Z=13,X+Y+2Z=7,2X+3Y-Z=12最好先消去什么3X+2Y+Z=13,X+Y+2Z=7,2X+3Y-
3X+2Y+Z=13,X+Y+2Z=7,2X+3Y-Z=12 最好先消去什么
3X+2Y+Z=13,X+Y+2Z=7,2X+3Y-Z=12 最好先消去什么
3X+2Y+Z=13,X+Y+2Z=7,2X+3Y-Z=12 最好先消去什么
最好的方法:
3X+2Y+Z=13①
X+Y+2Z=7②
2X+3Y-Z=12 ③
先将三个式子相加得
6X+6Y+2Z=32
3X+3Y+Z=16④
④-①得Y=16-13=3
将Y=3带入①得
3X+Z=7⑤
将Y=3带入③得
2X-Z=3⑥
⑤+⑥得
5X=10
X=2
将X=2带入⑤得
Z=1
所以方程组的解是X=2,Y=3,Z=1
祝你开心
试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y)
已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z
3x+2y+z=13 x+y+2z=7 2x+3y-z=12 x=?y=?z=?
{3x+2y+z=13 x+y+2z=7 2x+3y-z=12,求x,y,z
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证明 :x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0
{x+y+z=1;x+3y+7z=-1;z+5y+8z=-2
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若x+y+z=3y=2z,则x/x+y+z=?
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若X:Y:Z=5:6:7那么(Y-X):(Y+Z)和(X+2Y+3Z):(3X+2Y+Z)
六年级三元一次方程组.解下列方程组:(1)5x-3y+z=25x+2y-4z=3-5x+y-z=2(2)x-y-z=-13x_5y+7z=114x-y+2z=-1(3)9x-5y+z=-69x+y+4z=3-9x+3y-5z=0(4)x+y=22x+z=-27y+z=13