\[z² + 5z + 6 = 0\]
\[z_{1} + z_{2} = - 5\]
\[z_{1} \cdot z_{2} = 6 \Longrightarrow z_{1} = - 2;\ \ z_{2} = - 3\]
\[Ответ:z_{1} = - 2;\ \ z_{2} = - 3.\]