Answer:
[tex] {3}^{n + 2} + \: ({3}^{n + 3} - \: {3}^{n + 1} ) \\{ 3 }^{n + 2} + {3}^{n + 1} ({3}^{2} + 1) \\ {3}^{n + 2} + {3}^{n + 1} (9 + 1) \\ {3}^{n + 1} (3 + 10) \\ {3}^{n + 1} 30 \\ {3}^{n} \times 3 \times 30 = 90 \times {3}^{n}[/tex]
second one 13/313