1:7x+2y-z=7 2:6x-y+z=7 3:4x+3y+z=9 1：9x+4y+z+10 2：-9X+2y+3z=-6 3:3x-4y+2z=5 1:3x-5y+2z=1 2:4X+5y-z=5 3:x-5y+3z=-2 1：5x-3y+6z=-3 2:2X-y+3z=0 3:y+3z=6

(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. 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 {x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 x+y+z=14 7z=x+y+2 x+z=y ..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 已知x+2y-3z=0,5x-6y+7z=1;则x:y:z=?把“5z-6y+7z=1”改成“5x-6y+7z=0” 4X+3Y-2Z=-7,5X-6Y+Z=1,2X+Z=-2 4X+3Y-2Z=-7,5X-6Y+Z=1,2X+Z=-2 (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~ 若X:Y:Z=5:6:7那么(Y-X):(Y+Z)和(X+2Y+3Z):(3X+2Y+Z) 化简求值4x-{2x+3[x+2(4z-x)-2y]-7y}+6z其中x-y=-3,y-z=-1 x+y+z=6 x+2y+3z=14 y+1=z 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=? x+Y+Z=1 X+3Y+7Z=-1 X+5Y+8Z=2x+Y+Z=1X+3Y+7Z=-1X+5Y+8Z=2 2x-3y-z=-6 7x-y+2z=-17 x-y+z=-6 2x+5y+4z=6,3x+y-7z=-4,x+y-z=? 解方程：x+z=y (1) ,7z-(x+y)=2 (2) ,x+y+z=14 (3)