(7y-3z)-(8y-5z)=-y+2z(7y-3z)-(8y-5z)=7y-3z-8y+5z=(7y-8y)-(3z+5z)=-y-8z为什么是+2z?我觉得没变错,

{x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 (7y-3z)-(8y-5z)=-y+2z(7y-3z)-(8y-5z)=7y-3z-8y+5z=(7y-8y)-(3z+5z)=-y-8z为什么是+2z?我觉得没变错, （7y-3z)-(8y-5z)=?化简! x+Y+Z=1 X+3Y+7Z=-1 X+5Y+8Z=2x+Y+Z=1X+3Y+7Z=-1X+5Y+8Z=2 已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 求Y(Z)=Z(Z+2)/(3Z-7)(Z+1)的z反变换 2x+3y-z=11 2x+y-5z=8 -2+7y+z=19 {x+y+z=1 {x+3y+7z=-1 {x+5y+8z=2 已知关于x y z的方程组2x-3y+5z=7 x+2y-3z=8,则4x+y-z= 已知:x+y+z=0,5x-3y-z=0,求:5x-y+z/2x+8y+7z 的值 (4x-2y-z)-{5x-[8y-2z-(x-2y)]-x-(3y-10z)}=? (4x-2y-z)-{5x-[8y-2z-(x+y)]-2(3y-10z)}=?好难啊 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 x+y+z=1 x+3y+7z=-1 x+5y+8=2题错了 x+y+z=1 x+3y+7z=-1 x+5y+8z=2 -(7y-3z)-(8y-5z)计算! (7Y-3Z)-(8Y-5Z)化简 (7y-3z)-(8y-5z)得多少, x+y-z=3 y+z-x=5 z+x-y=7 求x,y,z