1.112

\(\displaystyle \frac{(3^n+3^{n-1})^2}{9^{n-1}}=\frac{(4\cdot3^{n-1})^2}{(3^2)^{n-1}}=16.\)

\(\displaystyle \frac{(5^n-5^{n-1})^3}{125^{n-1}}=\frac{(4\cdot5^{n-1})^3}{(5^3)^{n-1}}=64.\)

\(\displaystyle \frac{4^{n-2}}{(2^{n-1}-2^{n-2})^2}=\frac{2^{2n-4}}{(2^{n-2})^2}=1.\)