\[\left( x^{3} \cdot x^{2} \right)^{2} = \ *\ \cdot ( - x)^{3}\]
\[\left( x^{3 + 2} \right)^{2} = \ *\ \cdot \left( - x^{3} \right)\]
\[\left( x^{5} \right)^{2} = \ *\ \cdot \left( - x^{3} \right)\]
\[x^{10} = \ *\ \cdot \left( - x^{3} \right)\]
\[*\ = x^{10}\ :\left( - x^{3} \right)\]
\[*\ = - x^{10 - 3}\]
\[*\ = - x^{7}.\]