已知m^2+m-1=0,则-m^3-2m^2+2009=
问题描述:
已知m^2+m-1=0,则-m^3-2m^2+2009=
答
-m^3-2m^2+2009
=-m^3-m^2+m-m^2-m+1+2008
=-(m^3+m^2-m)-(m^2+m-1)+2008
=-m(m^2+m^-1)-(m^2+m-1)+2008
=2008