(χ-m)2-n(χ2-m2)=0
(χ-m)2-n(x+m)(χ-m)=0
(χ-m)2-(nx+nm)(χ-m)=0
(x-m)(x-m+nx+nm)=0
(x-m){(n+1)x+m(n-1)}=0
x1=m x2=m(n-1)/(n+1)