若2x+5y+4x=6,3x+y-7z=-4,那么x+y-z的值是多少?

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若2x+5y+4x=6,3x+y-7z=-4,那么x+y-z的值是多少?若2x+5y+4x=6,3x+y-7z=-4,那么x+y-z的值是多少?若2x+5y+4x=6,3x+y-7z=-4,那么x+y

若2x+5y+4x=6,3x+y-7z=-4,那么x+y-z的值是多少?
若2x+5y+4x=6,3x+y-7z=-4,那么x+y-z的值是多少?

若2x+5y+4x=6,3x+y-7z=-4,那么x+y-z的值是多少?
(2x+5y+4z)*a+(3x+y-7z)*b=(3b+2a)x+(5a+b)y-(7b-4a)z
3b+2a=K
5a+b=K
7b-4a=K
可得 b=3/2a
所以取a=2,b=3
(2x+5y+4z)*2+(3x+y-7z)*3=13x+13y-13z=13*(x+y-z)=2*6+3*-4=0
所以x+y-z=0

楼主第一个式子是不是写错了

我算出来等于0.不知道是不是对的。将两式联立，解出X=4Y+11Z-10，再将X代入，解出Z=0，Y=2，X=-2

2x+5y+4z=6 (1) 3x+y-7z=-4 (2)
(1)×2 4x+10y+8z=12 (3)
(2)×3 9x+3y-21z=-12 (4)
(3)+(4) 13x+13y-13z=0
即 x+y-z=0

若X:Y:Z=5:6:7那么(Y-X):(Y+Z)和(X+2Y+3Z):(3X+2Y+Z) 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 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 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=3：4：5,(1)求x+y分之z的值；（2）若x+y+z=6,求x,y,z. 三元一次方程组2x+z=3 3x+y-z=8 x+3y+2z=3 5x+2y-3z=2 x+2y+z=6 7x-2y-4z=262x+z=3 3x+y-z=8 x+3y+2z=3 5x+2y-3z=2 x+2y+z=6 7x-2y-4z=26 ..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 (1)2X+4Y+3Z=93X-2Y+5Z=115X-6Y+7Z=13(2)X:Y=3:2Y:Z=5:4X+Y+Z=66(3)3X-Y+Z=32X+Y-3Z=11X+Y+Z=13以上3个题目为三元一次方程~ 4X+3Y-2Z=-7,5X-6Y+Z=1,2X+Z=-2 4X+3Y-2Z=-7,5X-6Y+Z=1,2X+Z=-2 (4x-2y-z)-{5x-[8y-2z-(x-2y)]-x-(3y-10z)}=? 4x+9y=12 3y-2y+5z=11 5x-6y+7z=13 求：x y z等于多少 {5x-3y+z=2{5x+2y-4z=3{-5x+y-z=2 {x-y-z=-1{3x+5y+7z{4x-y+2x=-1 方程组3x+y-4z=1 2x-y-2z=6 5x+3y-3z= --1/2{负二分之一} x=?y=?z=?3x+2y+z=13 x+y+2z=7 2x+3y-z=12 x=?y=?z=?