m^2+m-1=0,m^3+2m^2+2004=?说明理由.
问题描述：
m^2+m-1=0,m^3+2m^2+2004=?说明理由.
答
m^3+2m^2+2004=m^2(m+2)+2004 把m^2=1-m代进去
=(1-m)(m+2)+2004
=m+2-m^2-2m+2004
=2006-(m+m^2)
=2006-1
=2005