\[(3a)^{3} - (2b)^{2} + 5b^{2} - 0,5a \cdot a^{2} =\]
\[= 9a^{3} - 4b^{2} + 5b^{2} - 0,5a^{3} =\]
\[= 8,5a^{3} + b^{2}.\]