x+x^-1=m x+x^-2=?
问题描述：
x+x^-1=m x+x^-2=?
答
x+x^-1=m
两边平方：
(x+x^(-1))^2=m^2
x^2+x^(-2)+2=m^2
x^2+x^(-2)=m^2-2那最后x+x^-2=?=m^2 - 2上边已经列出来了啊！是x+x^-2不是x^2+x^-2x+x^-1=mx^(-1)=m-xx^(-2)=(m-x)^2 = m^2-2mx+x^2x+x^-1=mx^2-1=mxx^2-mx-1=0x^2=mx+1x={m±根号(m^2+4)}/2x+x^(-2) = x+ m^2-2mx+x^2 【x^(-2) = m^2-2mx+x^2】= x^2-(2m-1)x+m^2= mx+1-(2m-1)x+m^2【x^2=mx+1】= m^2+1-(m-1)x= m^2+1-(m-1){m±根号(m^2+4)}/2