Question 97610
({{{ 2sqrt( 6 ) }}}+{{{ 7sqrt( 3 ) }}})({{{ 2sqrt( 6 ) }}}-{{{ 7sqrt( 3 ) }}})

if {{{ 2sqrt( 6 ) }}} = x
and {{{ 7sqrt( 3 ) }}} =y  then the given expression can be wriiten as

{{{(x+y) (x-y)}}}
{{{ x^2 - y^2 }}}

Substituting back the values of x and y we have

{{{ (2sqrt( 6 ))^2 - (7sqrt( 3 ))^2 }}} 

{{{4*6 - 49*3 }}}
{{{24 -  147}}}
{{{ 123 }}}