Question

giải giúp mik với !

Answer 1

\(a,\Leftrightarrow2\left(n-3\right)+5⋮n-3\\ \Leftrightarrow n-3\inƯ\left(5\right)=\left\{-5;-1;1;5\right\}\\ \Leftrightarrow n\in\left\{2;4;8\right\}\left(n\in N\right)\\ b,3B=3^2+3^3+...+3^{101}\\ \Leftrightarrow3B-B=3^{101}-3\\ \Leftrightarrow2B+3=3^{101}=3^n\\ \Leftrightarrow n=10`\)

Answer 2

a: \(\Leftrightarrow n-3\in\left\{1;-1;5\right\}\)

hay \(n\in\left\{4;2;8\right\}\)