\[1)\ f(x) = \left\{ \begin{matrix} 1 - x^{2}\ при\ x < 0 \\ x + 2\ \ \ при\ x > 0 \\ \end{matrix} \right.\ \]
\[a = 0:\]
\[\lim_{\begin{matrix} x \rightarrow 0 \\ x < 0 \\ \end{matrix}}\left( 1 - x^{2} \right) = 1 - 0 = 1;\]
\[\lim_{\begin{matrix} x \rightarrow 0 \\ x > 0 \\ \end{matrix}}(x + 2) = 0 + 2 = 2.\]
\[Ответ:\ \ 1;\ 2.\]
\[2)\ f(x) = \frac{3x - |x|}{2x};\ a = 0:\]
\[\lim_{\begin{matrix} x \rightarrow 0 \\ x < 0 \\ \end{matrix}}\frac{3x + x}{2x} = \lim_{\begin{matrix} x \rightarrow 0 \\ x < 0 \\ \end{matrix}}\frac{4x}{2x} = 2;\]
\[\lim_{\begin{matrix} x \rightarrow 0 \\ x > 0 \\ \end{matrix}}\frac{3x - x}{2x} = \lim_{\begin{matrix} x \rightarrow 0 \\ x > 0 \\ \end{matrix}}\frac{2x}{2x} = 1.\]
\[Ответ:\ \ 2;\ 1.\]
\[3)\ f(x) = \left\{ \begin{matrix} |x| - 1\ при\ x < - 1 \\ \sqrt{x + 2}\ при\ x > - 1 \\ \end{matrix} \right.\ \text{\ \ \ }\]
\[a = - 1:\]
\[\lim_{\begin{matrix} x \rightarrow - 1 \\ x < - 1 \\ \end{matrix}}\left( |x| - 1 \right) = 1 - 1 = 0;\]
\[\lim_{\begin{matrix} x \rightarrow - 1 \\ x > - 1 \\ \end{matrix}}\sqrt{x + 2} = \sqrt{- 1 + 2} = 1.\]
\[Ответ:\ \ 0;\ 1.\]
\[4)\ f(x) = \left\{ \begin{matrix} x^{2} - 2|x|\ при\ x < - 1 \\ x + 3\ \ \ \ \ \ \ \ \ при\ x > - 1 \\ \end{matrix} \right.\ \]
\[a = - 1:\]
\[\lim_{\begin{matrix} x \rightarrow - 1 \\ x < - 1 \\ \end{matrix}}\left( x^{2} - 2|x| \right) = 1 - 2 = - 1;\]
\[\lim_{\begin{matrix} x \rightarrow - 1 \\ x > - 1 \\ \end{matrix}}(x + 3) = - 1 + 3 = 2.\]
\[Ответ:\ - 1;\ 2.\]