N+3 N+1
3 - 3 - 2/ 11


Răspuns :


[tex] {3}^{n + 3} - {3}^{n + 1} - \frac{2}{11} = {3}^{n + 1} ( {3}^{2} - 1) - \frac{2}{11} = {3}^{n + 1} \times 8 - \frac{2}{11} [/tex]
sper ca am ajutat