1.5 Lösning 3b

\[ {3^{-2} \cdot 9^2 \over 27} \, = \, {3^{-2} \cdot (3^2)^2 \over 3^3} \, = \, {3^{-2} \cdot 3^4 \over 3^3} \, = \, {3^{-2+4} \over 3^3} \, = \, {3^2 \over 3^3} = 3^{2-3} \, = \, 3^{-1} \]