Question

Determinați Mulțimea A={n număr natural |3^n+1 <9^4}

Answer 1

${3}^{n + 1} < {9}^{4} \\ {3}^{n + 1} < ( {3}^{2} )^{4} \\ {3}^{n + 1} < {3}^{8} \\ n + 1 < 8 \\ n < 7 \\ \iff \: n\in\{0;1;2;3;4;5;6\}$