Решебник по алгебре и начала математического анализа 11 класс Алимов Задание 1474

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\[1)\ y = \cos{3x}\]

\[y(x + T) = y(x)\]

\[\cos{3(x + T)} = \cos{3x}\]

\[\cos(3x + 3T) = \cos{3x}\]

\[3T = 2\pi\]

\[T = \frac{2\pi}{3}.\]

\[Ответ:\ \ \frac{2\pi}{3}.\]

\[2)\ y = \sin\frac{x}{5}\]

\[y(x + T) = y(x)\]

\[\sin\frac{x + T}{5} = \sin\frac{x}{5}\]

\[\sin\left( \frac{x}{5} + \frac{T}{5} \right) = \sin\frac{x}{5}\]

\[\frac{T}{5} = 2\pi\]

\[T = 10\pi.\]

\[Ответ:\ \ 10\pi.\]

\[3)\ y = \sin x + tg\ x\]

\[y(x + T) = y(x)\]

\[\left\{ \begin{matrix} \sin{(x + T) = \sin x} \\ \text{tg}(x + T) = tg\ x\ \ \\ \end{matrix} \right.\ \text{\ \ }\]

\[\left\{ \begin{matrix} T = 2\pi \\ T = \pi\ \ \ \\ \end{matrix} \right.\ \ \]

\[T = 2\pi.\]

\[Ответ:\ \ 2\pi.\]