已知m²+2m-1=0,求m²+1/m²的值

已知m²+2m-1=0,求m²+1/m²的值
已知m²+2m-1=0,求m²+1/m²的值

已知m²+2m-1=0,求m²+1/m²的值
m²+2m-1=0
m≠0
两边同除以m,得
m+2-1/m=0
m-1/m=-2
m²+1/m²
=(m-1/m)²+2
=(-2)²+2
=6