m-1不等于0
△>0,(m-2)^2+4(m-1)>0
1/x1^2+1/x2^2=(x1^2+x2^2)/(x1x2)^2=[(x1+x2)^2-2x1x2]/(x1x2)^2
=[((m-2)/(m-1))^2+2/(m-1)](m-1)^2=(m-2)^2+2(m-1)^2=
m-1不等于0
△>0,(m-2)^2+4(m-1)>0
1/x1^2+1/x2^2=(x1^2+x2^2)/(x1x2)^2=[(x1+x2)^2-2x1x2]/(x1x2)^2
=[((m-2)/(m-1))^2+2/(m-1)](m-1)^2=(m-2)^2+2(m-1)^2=