(x-y+z)/(x+y+z)=(x-3x+4x)/(x+3x+4x)=1/4
(x-y+z)/(x+y+z)=(x-3x+4x)/(x+3x+4x)=2x/8x=1/4
x-3x+4x=2x x+3x+4x=8x 16x方
1\4
将y=3x,z=4x代入(x-y+z)/(x+y+z)=(x-3x+4x)/(x+3x+4x)=2x/8x=1/4
当y=3x,z=4x时,原式=(x-3x+4x)/(x+3x+4x) =2x/8x =1/4