Question 647613
{{{ root( 3,a )^((5/2)) }}}
Use the general rule:
{{{ ( a^b)^c = a^( b*c ) }}}
{{{ ( a^(1/3) )^(5/2) }}}
{{{ a^( (1/3)*(5/2) ) }}}
{{{ a^(( 5/6 )) }}}
That's all you can do, except maybe 
express it as {{{ root( 6,a )^5 }}}