x:y:z=1:3:5 (1)x+y+z=18(2)解这个三元一次方程组

已知 x/(y+z)+y/(z+x)+z/(x+y)=1求 (x*x)/(y+z)+(y*y)/(x+z)+(z*z)/(x+y)=? {x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 {x+y-z=11 y+z-x=5 z+x-y=1 {x+y-z=11,x-y-z=-5,x-y+z=1 x+Y+Z=1 X+3Y+7Z=-1 X+5Y+8Z=2x+Y+Z=1X+3Y+7Z=-1X+5Y+8Z=2 方程组 (1) x+2y-3z=12 x-3y+2z= - 13 x-y-z=0 (2) x+ y=z 5x-y+z=18 2x+5y+3z= -1 已知实数x y z满足x/(x+1)=y/(y+2)=z/(z+3)=(x+y+z)/3,求x+y+z的值 已知实数x y z满足x/(x+1)=y/(y+2)=z/(z+3)=(x+y+z)/3,求x+y+z的值 x+y+z=6 x+2y+3z=14 y+1=z {x+y+z=1 {x+3y+7z=-1 {x+5y+8z=2 {x+y+z=1 x-2y+3z=5 2x-3y-3z=-8 2x-y+3z=3 {3X+Y-2Z=-1 X+Y+Z=5 x-y+z=-1 5x+2y-z=6 4x-3y+2z=-5 x+y+z=-5,3x+y+z=1,4x+3y+2z=-2快 3x+2y+z=14 ,x+y+z=10,z+2x+3y=1 5 当x;y;z=1;3;5时,x+3y-z除以x-3y+z等于多少? 若x：y：z=1:3:5,求分式x+3y-z/x-3y+z的值 若x:y:z=1：3：5,求x+3y-z/x-3y+Z的值.