Answer:
[tex]x \sqrt{x} = \sqrt{216} [/tex]
square both sides:
[tex] {(x \sqrt{x}) }^{2} = {( \sqrt{216}) }^{2} [/tex]
solve the roots:
[tex]( {x}^{2} .x) = 216 \\ {x}^{3} = 216[/tex]
take a cube root on both sides:
[tex] \sqrt[3]{ {x}^{3} } = \sqrt[3]{216} [/tex]
solve the cube root:
[tex]x = 6[/tex]
