Question 77899
The given expression is: 


{{{sqrt (7)}}} (2 {{{ sqrt (3) }}} + 3 {{{ sqrt (7) }}})


This cna be written as: 



{{{ 2 * sqrt (7) * sqrt(3) }}} +  {{{ 3 * sqrt (7) * sqrt(7) }}} 



{{{ 2 * sqrt(21) }}} + {{{3 * 7 }}} 



{{{ 2 * sqrt(21) + 21 }}} 



We know that 21 can be written as: {{{ sqrt(21) * sqrt(21) }}} 


==>  {{{ 2 * sqrt(21) + sqrt(21) * sqrt(21) }}} 


Taking sqrt(21) as a common factor, we get:


{{{sqrt (21) * (2 + sqrt(21))}}} 


Hence, the solution.