因为有2根,所以 (m-2)^2+4(m-1)>或=0且m-1不等于0
设两根为x1,x2
则x1+x2= -(m-2)/(m-1) x1*x2=1-m
则1/x1^2+1/x2^2=[(x1+x2)^2-2*x1*x2]/(x1*x2)^2