T_{k+1}=x_{1}^{k+1}+x_{2}^{k+1}&=(x_{1}+x_{2})(x_{1}^{k}+x_2^{k})-x_{1}x_{2}(x_{1}^{k-1}+x_{2}^{k-1})\\
&=(x_{1}+x_{2})[(x_{1}+x_{2})(x_{1}^{k-1}+x_{2}^{k-1})-x_{1}x_{2](x_{1}^{k-2}+x_{2}^{k-2})]-x_{1}x_{2}(x_{1}^{k-1}+x_{2}^{k-1})\\
&=[(x_{1}+x_{2})^{2}-x_{1}x_{2}](x_{1}^{k-1}+x_{2}^{k-1})-x_{1}x_{2}(x_{1}^{k-2}+x_{2}^{k-2})\\
&=(27^{2}-14)(x_{1}^{k-1}+x_{2}^{k-1})-27\cdot14(x_{1}^{k-2}+x_{2}^{k-2})\\
&=715(x_{1}^{k-1}+x_{2}^{k-1})-378(x_{1}^{k-2}+x_{2}^{k-2})
\end{expres}
Bài viết đã được chỉnh sửa nội dung bởi Nobodyv3: 13-07-2021 - 23:10