\[1)\ A(3;\ - 4):\]
\[x = 3 > 0;\]
\[y = - 4 < 0.\]
\[Ответ:\ \ в\ IV.\]
\[2)\ B( - 3;\ 1):\]
\[x = - 3 < 0;\]
\[y = 1 > 0.\]
\[Ответ:\ \ во\ II.\]
\[3)\ C( - 4;\ - 5):\]
\[x = - 4 < 0;\]
\[y = - 5 < 0.\]
\[Ответ:\ \ в\ III.\]
\[4)\ D(1;\ 9):\]
\[x = 1 > 0;\]
\[y = 9 > 0.\]
\[Ответ:\ \ в\ I.\]