Question

02)A equação 3x = 81 em R vale: * A) 5. B) 3. C) 4. D) -3

Answer 1

$\Large\boxed{\begin{array}{l}\rm A\,equac_{\!\!,}\tilde ao~3^x=81\,em\,\mathbb{R}\,vale:\\\tt A)\,5\\\tt B)\,3\\\tt C)\,4\blacksquare\\\tt D)\!\,-\!3\\\underline{\boldsymbol{soluc_{\!\!,}\tilde ao\!:}}\\\begin{array}{c|c}\sf81&\sf3\\\sf27&\sf3\\\sf9&\sf3\\\sf3&\sf3\\\sf1\end{array}\\\sf 81=3^4\\\sf 3^x=81\\\sf 3^x=3^4\\\sf x=4\end{array}}$