[tex] { (\frac{1}{3} )}^{x} = 81 \\ { ({3}^{ - 1}) }^{x} = {3}^{4} \\ {3}^{ - x} = {3}^{4} \\ - x = 4 \\ x = - 4[/tex]
[tex](\frac{1}{3})^{x} = 81\\\\(\frac{1}{3})^{x} = 3^{4}\\\\Potegi \ sprowadzamy \ do \ jednakowych \ podstaw, zatem:\\\\(\frac{1}{3})^{x} = (\frac{1}{3})^{-4}\\\\\boxed{x = -4}[/tex]
