Answer :
Answer: -15
Given:
[tex]\sqrt[]{-15}\times\sqrt[]{-15}[/tex]Since the radical rule states that:
[tex]\begin{gathered} \sqrt[]{a}\sqrt[]{a}=a \\ \Rightarrow\sqrt[]{-15}\times\sqrt[]{-15}=-15 \end{gathered}[/tex]Therefore, the answer is -15.