設(shè)(y+z)/x=(z+x)/y=(x+y)/z=t
∴y+z=tx
z+x=ty
x+y=tz
三式相加
2(x+y+z)=t(x+y+z)
（t-2)(x+y+z)=0
∴x+y+z=0或t=2
∵x+y+z≠0
∴t=2
∴x+y=2z
(x+y-z)/(x+y+z)
=(2z-z)/(2z+z)
=1/3已知分式x-m分之x+m,當(dāng)x=-2時(shí),分式的值為0試化簡分析(-0.1x^2+0.2xyz)分之（m分之1x-m+1分之2 xy）寫出來再加5分當(dāng)x=-2時(shí)，(x+m)/(x-m)=0∴(-2+m)/(-2-m)=0∴m-2=0,m=2[x/m-2xy/(m+1)]/(-0.1x^2+0.2xyz)=[x/2-2/3*xy]/(-x^2/10+xyz/5)=(15-20y)/(-3x+6yz)=(20y-15)/(3x-6yz)對(duì)你的書寫，有地方讀不懂