[tex]6 \sqrt{10} \times ( - 2 \sqrt{5} ) = - 12 \sqrt{50} = - 60 \sqrt{2} [/tex]
[tex]6 \sqrt{10} \div ( - 2 \sqrt{5} ) = - 3 \sqrt{2} [/tex]
[tex] { - 2 \sqrt{5} }^{3} = { - 2 \sqrt{5} }^{2} \times ( - 2 \sqrt{5} ) = 20 \times ( - 2 \sqrt{5} ) = - 40 \sqrt{5} [/tex]
