已知m+1⼀m=1,则y=f(m)=m^2008+1⼀m^2005 急。。。

写错了 是m^2008+1⼀m^2015
2025-03-02 04:29:14
推荐回答(1个)
回答1:

∵m+1/m=1,∴m^2+1=m,∴m^2-m+1=0,
∴m=(1+√3i)/2=cos60°+isin60°,或m=(1-√3i)/2=cos(-60°)+isin(-60°)。

一、当m=cos60°+isin60°时,
m^2008
=(cos60°+isin60°)^2008=cos2008×60°+isin2008×60°
=cos(334×6×60°+4×60°)+isin(334×6×60°+4×60°)
=cos(180°+60°)+isin(180°+60°)=-cos60°-isin60°=-1/2-√3i/2。

m^2015
=(cos60°+isin60°)^2015=cos2015×60°+isin2015×60°
=cos(335×6×60°+5×60°)+isin(335×6×60°+5×60°)
=cos(360°-60°)+isin(360°-60°)=cos60°-isin60°=1/2-√3i/2。

∴m^2008+1/m^2015
=-1/2-√3i/2+1/(1/2-√3i/2)=-1/2-√3i/2+(1/2+√3i/2)/(1/4+3/4)=0。

二、当m=cos(-60°)+isin(-60°)时,
m^2008
=[cos(-60°)+isin(-60°)]^2008
=cos2008×60°-isin2008×60°=cos(334×6×60°+4×60°)-isin(334×6×60°+4×60°)
=cos(180°+60°)-isin(180°+60°)=-cos60°+isin60°=-1/2+√3i/2。

m^2015
=[cos(-60°)+isin(-60°)]^2015=cos2015×60°-isin2015×60°
=cos(335×6×60°+5×60°)-isin(335×6×60°+5×60°)
=cos(360°-60°)-isin(360°-60°)=cos60°+isin60°=1/2+√3i/2。

∴m^2008+1/m^2015
=-1/2+√3i/2+1/(1/2+√3i/2)=-1/2+√3i/2+(1/2-√3i/2)/(1/4+3/4)=0。

综上一、二所述,得:m^2008+1/m^2015=0。