2. \(\frac{(5^n-5^{n-1})^3}{125^{n-1}}\)

\(5^n=5\cdot5^{n-1}\), ал \(125=5^3\). Сондықтан:

\[\frac{(5^n-5^{n-1})^3}{125^{n-1}}=\frac{(5\cdot5^{n-1}-5^{n-1})^3}{(5^3)^{n-1}}\]

\[=\frac{(4\cdot5^{n-1})^3}{5^{3n-3}}=\frac{64\cdot5^{3n-3}}{5^{3n-3}}=64.\]

Жауабы: \(64\).