2) а)
\[ 2^{3}:2^{6} = 2^{3-6} = 2^{-3} = \frac{1}{2^3} = \frac{1}{8} \]
2) б)
\[ 5^{5}:5^{-1} = 5^{5-(-1)} = 5^{5+1} = 5^6 \]