(m+n)x²-[(m+n)+(n-5m)]x+(n-5m)]=0 (m+n)x²-(m+n)x-(n-5m)x+(n-5m)]=0 (m+n)x(x-1)-(n-5m)(x-1)=0 [(m+n)x-(n-5m)](x-1)=0 所以 m+n≠0,x=(n-2m)/(m+n),x=1 m+n=0,x=1
