回復 8# deca0206 的帖子
填充第2題
\(\begin{align}
& \alpha =2\omega ,\beta =2{{\omega }^{2}},\gamma =2{{\omega }^{3}},\delta =2{{\omega }^{4}},\omega =\cos \frac{2\pi }{5}+i\sin \frac{2\pi }{5} \\
& {{\omega }^{5}}=1 \\
& {{\omega }^{4}}+{{\omega }^{3}}+{{\omega }^{2}}+\omega =-1 \\
& f\left( \alpha \right)+f\left( \beta \right)+f\left( \gamma \right)+f\left( \delta \right)={{2}^{3}}\left( {{\omega }^{3}}+\omega +{{\omega }^{4}}+{{\omega }^{2}} \right)+{{2}^{2}}\left( {{\omega }^{2}}+{{\omega }^{4}}+\omega +{{\omega }^{3}} \right)+4=-8 \\
\end{align}\)
[ 本帖最後由 thepiano 於 2015-8-23 12:11 PM 編輯 ]