e) 3n+2 + 5.3n + 1 = 216
=> 3n . 32 + 5.3n . 31 = 216
=> 3n . 9 + 15.3n = 216
=> 3n ( 9 + 15) = 216
=> 3n . 24 = 216
=> 3n = 9
=> n = 2
f) 5n + 1 - 5n - 1 = 1254 . 23 . 37
=> 5n . 5 - 5n . 1/5 = 1254 . 23 . 37
=> 5n ( 5 - 1/5) = 1254 . 23 . 37
=> 5n . 24/5 = 1254 . 23 . 37
=> n không thỏa mãn
a,\(3^{n+2}+5.3^{n+1}=216\)
\(3^n.9+5.3^n.3=216\)
\(3^n\left(9+5.3\right)=216\)
\(3^n.24=216\)
\(3^n=9\Rightarrow n=2\)