\[x_1 = \frac{(-1)^1 + 2}{5} = \frac{-1 + 2}{5} = \frac{1}{5}\]
\[x_{10} = \frac{(-1)^{10} + 2}{5} = \frac{1 + 2}{5} = \frac{3}{5}\]
\[x_{2k} = \frac{(-1)^{2k} + 2}{5} = \frac{1 + 2}{5} = \frac{3}{5}\]
\[x_{2k-1} = \frac{(-1)^{2k-1} + 2}{5} = \frac{-1 + 2}{5} = \frac{1}{5}\]
Ответ: 1) \(\frac{1}{5}\); 2) \(\frac{3}{5}\); 3) \(\frac{3}{5}\); 4) \(\frac{1}{5}\)