\[z_{1} = 9y^{2} - 4 - 10xi;\ \]
\[z_{2} = 8y^{2} + 20i^{7}.\]
\[1)\ z_{2} = 8y^{2} + 20i \bullet i^{6} =\]
\[= 8y^{2} + 20i \bullet \left( i^{2} \right)^{3} =\]
\[= 8y^{2} + 20i \bullet ( - 1)^{3} = 8y^{2} - 20i.\]
\[2)\ Действительная\ часть:\]
\[9y^{2} - 4 = 8y^{2}\]
\[y^{2} = 4\]
\[y = \pm 2.\]
\[3)\ Мнимая\ часть:\]
\[- 10x = - ( - 20)\]
\[- 10x = 20\]
\[x = - 2.\]
\[Ответ:\ \ ( - 2;\ - 2);\ ( - 2;\ 2).\]