4x+5y-6z=0 x+2y-7z=0 且xyz≠0 试求 2x²+y²-6z² —————— x²+5y²+3z²2x²+y²-6z² —————x²+5y²+3z²

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4x+5y-6z=0x+2y-7z=0且xyz≠0试求2x²+y²-6z²——————x²+5y²+3z²2x²+y²-

4x+5y-6z=0 x+2y-7z=0 且xyz≠0 试求 2x²+y²-6z² —————— x²+5y²+3z²2x²+y²-6z² —————x²+5y²+3z²
4x+5y-6z=0 x+2y-7z=0 且xyz≠0 试求 2x²+y²-6z² —————— x²+5y²+3z²
2x²+y²-6z²
—————
x²+5y²+3z²

4x+5y-6z=0 x+2y-7z=0 且xyz≠0 试求 2x²+y²-6z² —————— x²+5y²+3z²2x²+y²-6z² —————x²+5y²+3z²
将z看成已知数
4x+5y=6z①
x+2y=7z②
可解得②×4-①可得3y=22z
y=22/3z
x=7z-2y=-23/3z
代入计算式有
计算式=[2*(-23/3)²+(22/3)²-6]z²/{[(-23/3)²+5*(22/3)²+3]z²}
=(2*23²+22²-6*3²)/(23²+5*22²+3*3²)
=1488/2976=1/2

令Z=1，带入上式得x=-23/3,y=22/3，
因此令z=3，得x=-23，y=22
带入分式得(2*x^2+y^2-6*z^2)/(x^2+5*y^2+3*z^2)=1/2

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 已知4x-3y-6z=0,x+2y-7z=0,求5x+2y-z/2x-3y-10z 三元一次方程解 1.{x+y-z=5 {3x+2y+z=2 {2x-2y+z=-31.{x+y-z=5 2.{9x-5y+x=-6 3.{x-y=3 4.{x+y=3 5.{4x-2y+z=7{3x+2y+z=2 {9x+y-2z=3 {x+z=7 {y+z=4 {2x-y-3z=28{2x-2y+z=-3 {-9x+3y-5z=0 {y-z=6 {z+x=5 {x+y-2z=13 已知x,y,z,满足方程组x-2y+z=0,7x+4y-5z=0 X-Y-Z=0 X+Y-3Z=4 2X-5Y+7Z=21 x+y+z=4x-5y=y-x+6z,xyz不等0,x:y:z=? 设z≠0 x、y、z 满足4x-7y-5z=0 2x-y-z=0 求x：y 设z≠0,x、y、z满足4x-7y-5z=0、2x-y-z=0,求x:y 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,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=? 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是一个方程组,那么x-y+z/x+y+z的值等于已知x.y.z满足x-2y+z=0且7x+4y-5z=0,求x:y:z的值已知x、y、z满足x—2y+z=0 7x+4y—5z=0 ,求x：y：z 已知x,y,z满足方程组x-2y+z=0 7x+4y-5z=0求x:y:z的值已知：4x-3y-6z=0,x+2y-7z=0.求出x-y+z÷x+y+z=?