\( \Rightarrow \)\({x^3} = 9\sqrt 3 + 11\sqrt 2 \)
\( = 6\sqrt 3 + 3\sqrt 3 + 9\sqrt 2 + 2\sqrt 2 \)
\( = 3\sqrt 3 + 2\sqrt 2 + 6\sqrt 3 + 9\sqrt 2 \)
\( = 3\sqrt 3 + 2\sqrt 2 + 3(2\sqrt 3 + 3\sqrt 2 )\)
\( = 3\sqrt 3 + 2\sqrt 2 + 3\sqrt 2 \,.\,\sqrt 3 (\sqrt 2 + \sqrt 3 )\)
\( = {(\sqrt 3 )^3} + {(\sqrt 2 )^3} + 3.\sqrt 2 .\sqrt 2 \,(\sqrt 3 + \sqrt 2 ) = {(\sqrt 3 + \sqrt 2 )^3}\)
So, \({x^3} = {(\sqrt 3 + \sqrt 2 )^3}\)
\(x = \sqrt 3 + \sqrt 2 \).