Question 77896
I presume that the 567 is meant to be {{{sqrt(567)}}}.
{{{(18+sqrt(567))/9}}}
{{{(18+sqrt(7*81))/9}}}
{{{(18+9*sqrt(7))/9}}}
Take out a common factor of 9 from the top terms.
{{{9(2+sqrt(7))/9}}}
{{{cross(9)(2+sqrt(7))/cross(9)}}}
{{{2+sqrt(7)}}}