Răspuns :
Foloesti folosesti formula de la progresii geometrice:
[tex] \frac{ 3^{29}-1 }{3-1} [/tex].
[tex] \frac{ 3^{29}-1 }{3-1} [/tex].
[tex]1+3+3^2+......+3^2^9= \\ = \frac{3^2^9^+^1-1}{3-1}= \\ = \frac{3^3^0-1}{2} [/tex]