\[\boxed{\mathbf{8}.}\]
\[1)\ \left( 1\frac{1}{3} + 3n \right)^{2} = \left( \frac{4}{3} + 3n \right)^{2} =\]
\[= \frac{16}{9} + 8n + 9n^{2}\]
\[2)\ \left( 0,4a^{2} - 5b \right)^{2} = 0,16a^{4} -\]
\[- 4a^{2}b + 25b^{2}\]
\[3)\ ( - 3p + 10q)^{2} = 9p^{2} -\]
\[- 60pq + 100q^{2}\]
\[4)\ ( - 6k - 0,5n)^{2} = 36k^{2} +\]
\[+ 6kn + 0,25n^{2}\]
\[5)\ \left( a^{2} + 4 \right)^{3} = a^{6} + 12a^{4} +\]
\[+ 48a^{2} + 64\]
\[6)\ (0,2 - b)^{3} = 0,008 - 0,12b +\]
\[+ 0,6b^{2} - b^{3}\]
\[7)\ ( - 3 - x)^{3} = - 27 - 9x^{2} -\]
\[- 27x - x^{3}\]
\[8)\ \left( - \frac{1}{3} + a \right)^{3} = - \frac{1}{27} + \frac{1}{3}a -\]
\[- a^{2} + a^{3}\]
\[9)\ \left( (2 - x)(2 + x) \right)^{2} =\]
\[= \left( 4 - x^{2} \right)^{2} = 16 - 8x^{2} + x^{4}\]