Question

u (S) ; S = 1 +3+3 la puterea a doua + ....+3 la puterea 2015

Answer 1

progresie geometrica cu ratia 3
avem formula S(n) =$b1 * \frac{1-q^n}{1-q}$

S(2015) = 1 * $\frac{1 - 3 ^{2015}}{1-3}$
S(2015) = $-\frac{1 - 3^{2015}}{2}$

desi..nu prea sunt sigur de raspuns cred ca asa se face