Giải các phương trình, hệ phương trình sau:
\(1) \,{x^2} - 7x + 10 = 0 \) \(2) \,{x^4} - 5{x^2} - 36 = 0 \) \(3) \, \left \{ \begin{array}{l}2x - y = - 7 \ \2x + 7y = 1 \end{array} \right. \)
A.\(\begin{array}{l}1)\,\,S = \left\{ {2; - 5} \right\}\\2)\,\,S = \left\{ { - 1;1} \right\}\\3)\,\,\left( {x;y} \right) = \left( { - 3; - 1} \right)\end{array}\)
B.\(\begin{array}{l}1)\,\,S = \left\{ { - 2;5} \right\}\\2)\,\,S = \left\{ { - 2;2} \right\}\\3)\,\,\left( {x;y} \right) = \left( {3; - 1} \right)\end{array}\)
C.\(\begin{array}{l}1)\,\,S = \left\{ {2;5} \right\}\\2)\,\,S = \left\{ { - 3;3} \right\}\\3)\,\,\left( {x;y} \right) = \left( { - 3;1} \right)\end{array}\)
D.\(\begin{array}{l}1)\,\,S = \left\{ { - 2; - 5} \right\}\\2)\,\,S = \left\{ { - \sqrt 2 ;\sqrt 2 } \right\}\\3)\,\,\left( {x;y} \right) = \left( {3;1} \right)\end{array}\)