\[\boxed{\mathbf{745}\mathbf{.}}\]
\[y = tg\ x;\]
\[1)\left\lbrack - \frac{\pi}{4};\ \frac{\pi}{3} \right\rbrack - монотонно\ \]
\[возрастает:\]
\[y_{\min} = tg\left( - \frac{\pi}{4} \right) = - tg\frac{\pi}{4} = - 1;\]
\[y_{\max} = tg\frac{\pi}{3} = \sqrt{3}.\]
\[Ответ:\ \ E(y) = \left\lbrack - 1;\ \sqrt{3} \right\rbrack.\]
\[2)\left( \frac{3\pi}{4};\frac{3\pi}{2} \right) - монотонно\ \]
\[возрастает:\]
\[y_{\min} = tg\frac{3\pi}{4} = tg\left( \frac{\pi}{2} + \frac{\pi}{4} \right) =\]
\[= - ctg\frac{\pi}{4} = - 1;\]
\[y_{\max} = tg\frac{3\pi}{2} = tg\left( \pi + \frac{\pi}{2} \right) =\]
\[= \text{tg}\frac{\pi}{2} - не\ существует.\]
\[Ответ:\ \ E(y) = ( - 1;\ + \infty).\]
\[3)\ (0;\ \pi) - \ имеет\ разрыв\ в\ \]
\[точке\ \frac{\pi}{2}.\]
\[\left( 0;\ \frac{\pi}{2} \right):\ \ \]
\[y_{\min} = tg\ 0 = 0;\]
\[y_{\max} = tg\frac{\pi}{2} - не\ существует.\]
\[\left( \frac{\pi}{2};\ \pi \right):\]
\[y_{\min} = tg\frac{\pi}{2} - не\ существует;\]
\[y_{\max} = tg\ \pi = 0.\]
\[Ответ:\ \ \]
\[E(y) = ( - \infty;\ 0) \cup (0;\ + \infty).\]
\[4)\left\lbrack \frac{\pi}{4};\ \frac{3\pi}{4} \right\rbrack - имеет\ разрыв\ в\ \]
\[точке\ \frac{\pi}{2}.\]
\[\left\lbrack \frac{\pi}{4};\ \frac{\pi}{2} \right):\ \ \]
\[y_{\min} = tg\frac{\pi}{4} = 1;\]
\[y_{\max} = \frac{\pi}{2} - не\ существует.\]
\[\left( \frac{\pi}{2};\ \frac{3\pi}{4} \right\rbrack:\]
\[y_{\min} = tg\frac{\pi}{2} - не\ существует;\]
\[y_{\max} = tg\frac{3\pi}{4} = tg\left( \frac{\pi}{2} + \frac{\pi}{4} \right) =\]
\[= - ctg\frac{\pi}{4} = - 1.\]
\[Ответ:\ \ \]
\[E(y) = ( - \infty;\ - 1\rbrack \cup \lbrack 1;\ + \infty).\]