若2x+5y-4z=0.3x+9y-7z=0,则x+y-z的值为------------------

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若2x+5y-4z=0.3x+9y-7z=0,则x+y-z的值为------------------若2x+5y-4z=0.3x+9y-7z=0,则x+y-z的值为------------------

若2x+5y-4z=0.3x+9y-7z=0,则x+y-z的值为------------------
若2x+5y-4z=0.3x+9y-7z=0,则x+y-z的值为------------------

若2x+5y-4z=0.3x+9y-7z=0,则x+y-z的值为------------------
2x+5y-4z=0,.(1) 3x+9y-7z=0.(2) (2)-(1),得 x+4y-3z=0.(3) (1)-(3),得 x+y-z=0 所以 x+y-z的值为0(不懂欢迎追问!

若2x+5y-4z=0.3x+9y-7z=0,则x+y-z的值为------------------ 若4x=7y+5z,2x+y=z,则x:y:z的值为 若x+2y-9z=0,x-2y+5z=0,(x.y.z≠=0)求2x平方+3y平方+7z平方/x平方-4y平方+4z平方 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 ..1.x+y+z=26,2.4y+3z=7,y-z=1,3x+2z=17,x+2y-z=18 9x-7y=173.x-7y+3z=17 4.2x+4y+3z=95x-6y-z=24 3x-2y+5z=113x+7y-2z=1 5x-6y+7z=131.x+y+z=26,y-z=1x+2y-z=18 2.4y+3z=7,3x+2z=11,9x-7y=17 3.x-7y+3z=17 5x-6y-z=24 3x+7y-2z=14.2x+4y+3z=93x-2y+5z=11 5x-6y+7z=13 若x,y,z成等差数列,则(z-x)^2-4(x-y)(y-z)= 已知2x+3y-4z=7 3x-2y+z=3 x+5y+9z=20 则 x+y+z= 若x :y :z=2 :3 :7 .且 x-2y+3z=34 则 x= y= z=? x+y=5 2x+3y-z=9 x-y+z=4 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 三(四)元一次方程组!1.2z-6=-2(x+3y)3(5y+x)=6-7z4(x+z)=9+9y2.2x-5y=-117y+4z=55x+2z=23.0.4x+0.3y-0.2z=40.6x-0.5y+0.3z=50.3x+0.2y+0.5z=224.x/2+3y/4+5z/3=455.1x+6y/5-4z=150.1x-0.4y+4z/5=55.x+y=7y-z=1z+2u=4u-3x=-11 若X:Y:Z=5:6:7那么(Y-X):(Y+Z)和(X+2Y+3Z):(3X+2Y+Z) 若z≠0,且4x=7y+5z,2x+y=z,求x,y,z的值 若2x+5y-4z=0,3x+9y-7z=0,则x+y-z的值为 若x+2y-9z=0,z-3y-5z=0,(xyz≠0)求:x²-4y²+9z²分之(2x²+3y²+7z²)若x+2y-9z=0,z-3y-5z=0,(xyz≠0),求:(x²-4y²+9z²)分之(2x²+3y²+7z²)的值. 4x+9y=12 3y-2y+5z=11 5x-6y+7z=13 求:x y z等于多少 已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 若3x+7y+z=5,4x+10y+z=3,则x+y+z=? 2x+5y+4z=6,3x+y-7z=-4,x+y-z=?