Agustín Valverde Ramos edited Soluci_n_Tenemos_que_demostrar__.md  over 8 years ago

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Solución: Tenemos que demostrar que \(P(\pi/5)=0\)  \[  \begin{aligned}  P(\pi/5)&=16\cos^5(\pi/5)-20\cos^3(\pi/5)+5\cos(\pi/5)+1 P(\pi/5)&=\underbrace{16\cos^5(\pi/5)-20\cos^3(\pi/5)+5\cos(\pi/5)}+1  =\\\ &\stackrel{(*)}{=}\cos(5\cdot\pi/5)+1 =\cos\pi+1=-1+1=0  \end{aligned}  \]