3x+7y+z=8,2x+3y+4z=7,则x+2y+z的值为多少?

已知关于x y z的方程组2x-3y+5z=7 x+2y-3z=8,则4x+y-z= {x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 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 3x+2y+z=3 2x=4-3z=-8 x+y-2z=-4 2x+y+3z=7 解下列三元一次方程组:(1)x-z=4,x+y-z=-1,2y-z=1 (2)3x+4z=7,2x+3y+z=9,x-y+z=8 解方程：{2x+3y+z=7,x+y+z=4,3x+y-z=-4{2x+3y+z=7,x+y+z=4,3x+y-z=-4要过程 x+Y+Z=1 X+3Y+7Z=-1 X+5Y+8Z=2x+Y+Z=1X+3Y+7Z=-1X+5Y+8Z=2 x：y：z=3:4:7 2x-3y+z=18 求：3x-2y+z x+2y+4z=17 2x+y+z=7 3x+y+2z=11 解三元一次方程：x+y-z=0,2x+y+z=7,x-3y+z=8 解方程组x+y-z=0,2x+y+z=7,x-3y+z=8 {x+y+z=1 {x+3y+7z=-1 {x+5y+8z=2 2x+5y+4z=6,3x+y-7z=-4,x+y-z=? X-Y-Z=0 X+Y-3Z=4 2X-5Y+7Z=21 3x+7y+4z=35,x+5y+2z=40,x+y+z=( ) {x+y+z=1 {x+3y+7z=2 {x+5y+19z=4 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