Simplify the following by reducing the index to the lowest possible form.
7.
[tex] \sqrt[ 4]{36x {}^{2} y {}^{2} } [/tex]
8.
[tex] \sqrt[6]{100m {}^{4} } [/tex]
9.
[tex] \sqrt[6]{216x {}^{3}y {}^{3} } [/tex]
10.
[tex] \sqrt[8]{81x {}^{4} } [/tex]
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