为什么X:Y:Z=1:3:5,就Y=3X

为什么X:Y:Z=1:3:5,就Y=3X x+y-z=3 y+z-x=5 z+x-y=7 求x,y,z x/2=y/3=z/5 x+3y-z/x-3y+z {x+y+z=1;x+3y+7z=-1;z+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 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=3:5 y:z=6:1,求x:y:z( ):( ):( ) 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 已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. matlab中为啥没有反映syms x y X Y Zx=0:0.1:10;y=0:0.1:10;[X,Y]=meshgrid(x,y);X.^2.*Z.^3+9.*Y.^2.*Z.^3/80==(X.^2+9.*Y.^2/4+Z.^2-1)^3;surf(X,Y,Z)回车之后就没任何反映了,为什么. {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=-5,3x+y+z=1,4x+3y+2z=-2快 3x+2y+z=14 ,x+y+z=10,z+2x+3y=1 5 x-y+z=-1 5x+2y-z=6 4x-3y+2z=-5 {x+y+z=1 {x+3y+7z=-1 {x+5y+8z=2 当x;y;z=1;3;5时,x+3y-z除以x-3y+z等于多少?