Question 953965
Already done yesterday.


{{{729=27*27=3^3*3^3=3^6}}}


Look on the inner radical first.
{{{(3^6*x^6)^(1/2)}}}
{{{3^3*x^3}}}
actually because of the square rooting,
{{{-(3x)^3}}}  or  {{{(3x)^3}}}


That is the expression in the outer radical, so revise:

{{{(-3^3*x^3)^(1/3)}}}   OR   {{{(3^3*x^3)^(1/3)}}}


completed result:
{{{highlight(-3x)}}}  or  {{{highlight(3x)}}}