\[\boxed{\mathbf{877}\mathbf{.}}\]
\[1)\ f(x) = x^{2} - 2x\ x_{0} = 3:\]
\[f^{'}(x) = \left( x^{2} \right)^{'} - (2x)^{'} = 2x - 2\]
\[f^{'}(3) = 2 \bullet 3 - 2 = 6 - 2 = 4\]
\[f(3) = 3^{2} - 2 \bullet 3 = 9 - 6 = 3\]
\[y = 3 + 4(x - 3) =\]
\[= 3 + 4x - 12 = 4x - 9.\]
\[Ответ:\ \ y = 4x - 9.\]
\[2)\ f(x) = x^{3} + 3x\text{\ \ }x_{0} = 3:\]
\[f^{'}(x) = \left( x^{3} \right)^{'} + (3x)^{'} = 3x^{2} + 3\]
\[f^{'}(3) = 3 \bullet 3^{2} + 3 = 3 \bullet 9 + 3 =\]
\[= 27 + 3 = 30\]
\[f(3) = 3^{3} + 3 \bullet 3 = 27 + 9 = 36\]
\[y = 36 + 30(x - 3) =\]
\[= 36 + 30x - 90 = 30x - 54.\]
\[Ответ:\ \ y = 30x - 54.\]
\[3)\ f(x) = \sin x\ x_{0} = \frac{\pi}{6}:\]
\[f^{'}(x) = \left( \sin x \right)^{'} = \cos x\]
\[f^{'}\left( \frac{\pi}{6} \right) = \cos\frac{\pi}{6} = \frac{\sqrt{3}}{2}\]
\[f\left( \frac{\pi}{6} \right) = \sin\frac{\pi}{6} = \frac{1}{2}\]
\[y = \frac{1}{2} + \frac{\sqrt{3}}{2}\left( x - \frac{\pi}{6} \right) =\]
\[= \frac{\sqrt{3}}{2}x + \frac{1}{2} - \frac{\pi\sqrt{3}}{12}.\]
\[Ответ:\ \ y = \frac{\sqrt{3}}{2}x + \frac{1}{2} - \frac{\pi\sqrt{3}}{12}.\]
\[4)\ f(x) = \cos x\text{\ \ }x_{0} = \frac{\pi}{3}:\]
\[f^{'}(x) = \left( \cos x \right)^{'} = - \sin x\]
\[f^{'}\left( \frac{\pi}{3} \right) = - \sin\frac{\pi}{3} = - \frac{\sqrt{3}}{2}\]
\[f\left( \frac{\pi}{3} \right) = \cos\frac{\pi}{3} = \frac{1}{2}\]
\[y = \frac{1}{2} - \frac{\sqrt{3}}{2}\left( x - \frac{\pi}{3} \right) =\]
\[= - \frac{\sqrt{3}}{2}x + \frac{1}{2} - \frac{\pi\sqrt{3}}{6}.\]
\[Ответ:\ \ y = - \frac{\sqrt{3}}{2}x + \frac{1}{2} - \frac{\pi\sqrt{3}}{6}.\]