Question 54295
{{{ 6sqrt(2)-6sqrt(7) }}}
For simplicity, lets rename the roots
{{{ sqrt(2) = x}}} and {{{ sqrt(7) = y }}}
place these back in the original equation
{{{ 6x-6y }}}
This is as simple as it gets.  You can not add and subtract variables that are different, so your original equation ...
{{{ 6sqrt(2)-6sqrt(7) }}}
it is no different ... it is in simplest form.