\[\begin{array}{l} {\text{Решите систему:}}\\ \left\{ \begin{array}{l} x + y = 5\\ {x^3} + {y^3} = 35 \end{array} \right. \end{array}\]

\[\left\{ \begin{array}{l} \sqrt {x + y} + \sqrt {{x^2} + xy} = 3 \hfill \\ x + y + {x^2} + xy = 5 \hfill \\ \end{array} \right.\]