设m^2+m-1=0,求m^3+2m^2+2005的值

设m^2+m-1=0,求m^3+2m^2+2005的值
设m^2+m-1=0,求m^3+2m^2+2005的值

设m^2+m-1=0,求m^3+2m^2+2005的值
设m^2+m-1=0,求m^3+2m^2+2005的值
由m^2+m-1=0,
m^3+2m^2+2005
= m(m^2+m-1+1+m)+2005
=m^2+m+2005
=m^2+m-1+2006
=2006
所以m^3+2m^2+2005的值=2006

2006
m3+m2=m
so m3+2m2=m+m2=1
1+2005=2006

把它分解就OK 了!
m^2+m-1=0
m^2+m=1
m^3+2m^2+2005=m(m^2+2m)+2005 =m(1+m)+2005= 1+2005=2006

(m+1/2)^2=5/4
m=(1+更号5)/2 或 (1-更号5)/2
然后就能算了