Question 571451
{{{ ( 6 + sqrt(5) )*( 6 - sqrt(5) ) }}}
{{{ 36 + 6*sqrt(5) - 6*sqrt(5) - 5 }}}
{{{ 31 }}}
You can check this:
{{{ sqrt(5) = 2.23607 }}}
{{{ ( 6 + 2.23607 )*( 6 - 2.23607 ) }}}
{{{ 8.23607 * 3.76393 = 30.99999096 }}}
close enough