\((\dfrac{1}{3}+3i)^3\)
\(=(\dfrac{1}{3})^3+(3i)^{3}+3(\dfrac{1}{3}(3i)(\dfrac{1}{3}+3i))\)
\(=\dfrac{1}{27}-27i+i+9i^2\)
\(=\dfrac{1}{27}-27i+i-9\)
\(=\dfrac{-242}{27}-26i\) (Ans.)