\[\boxed{\mathbf{30}\mathbf{.}}\]
\[1)\ \sqrt[3]{- 8} = \sqrt[3]{( - 2)^{3}} = - 2\]
\[2)\ \sqrt[15]{- 1} = \sqrt[15]{( - 1)^{15}} = - 1\]
\[3)\ \sqrt[3]{- \frac{1}{27}} = \sqrt[3]{\left( - \frac{1}{3} \right)^{3}} = - \frac{1}{3}\]
\[4)\ \sqrt[5]{- 1024} = \sqrt[5]{( - 4)^{5}} = - 4\]
\[5)\ \sqrt[3]{- 34^{3}} = - \sqrt[3]{34^{3}} = - 34\]
\[6)\ \sqrt[7]{- 8^{7}} = - \sqrt[7]{8^{7}} = - 8\]