Решебник по алгебре 9 класс Мерзляк Задание 699

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\[1)\ b_{1} = 18,\ \ b_{n + 1} = - \frac{b_{n}}{3}\]

\[b_{2} = - \frac{18}{3} = - 6\]

\[b_{3} = \frac{6}{3} = 2\]

\[b_{4} = - \frac{2}{3}\]

\[b_{5} = \frac{2}{3}\ :3 = \frac{2}{9}\]

\[2)\ b_{1} = - 1,\ \ b_{2} = 2,\ \ \]

\[b_{n + 2} = \ b_{n}^{2} + 2b_{n + 1}\]

\[b_{3} = ( - 1)^{2} + 2 \cdot 2 = 1 + 4 = 5\]

\[b_{4} = 2^{2} + 2 \cdot 5 = 4 + 10 = 14\]

\[b_{5} = 5² + 2 \cdot 14 = 25 + 28 = 53\]