m^2+m-1=0 求m^3+2m^2+2008=?

题目

m^2+m-1=0 求m^3+2m^2+2008=?
速求

答案

m^2+m=1 m^3+2m^2+2008
m^2+m+m=1+m =m(m^2+2m)+2008
m^2+2m=1+m =m(1+m)+2008
=m^2+m+2008
=1+2008
=2009