x=-7,有=12,z=-15,则x-y-z的值为____,x-（y-z）的值____

x=-7,有=12,z=-15,则x-y-z的值为____,x-（y-z）的值____ fangchengzu:X+Z=Y 7Z=X+Y+Z X+Y+Z=14 (x+y-z)(x-y+z)= 解方程组 x+y+z=-7 x-y=12 x+y-z=6 X/4=Y/5=Z/7则x+y+z/z=? 解方程 x(x+y+z)=6 y(x+y+z)=12 z(x+y+z)=18 解方程组{x(x+y+z)=6,y(x+y+z)=12,z(x+y+z)=18 x+y-z=3 y+z-x=5 z+x-y=7 求x,y,z X+Y+Z=? 已知(y+z)/x=(z+x)/y=(x+y)/z,则(y+z)/x的值是多少 x/y=(x+z)/(y+z)y/z=(x+y)/(x+z) x+y=8 y+z=12 x+z=10 x+y+z= x+y=8 y+z=12 x+z=10 x+y+z= x-4y+z=-302x+y-z=18x--y-z=7 x+y+z=14 7z=x+y+2 x+z=y 若x+y+z=3y=2z,则x/x+y+z=? x+y+z=15 x+5y+10z=70 x,y,z,各是几? x+y+z=15 x+5y+10z=70 x,y,z,各是几?