Question

Calculati 3^0+3^1+...+3^2014)*2 supra 3^2015-1

Answer 1

S=3^0+3^1+...+3^2014 ( suma progresie geometrica de ratie 3)
S= 1*$\frac{3^{2015}-1}{3-1}= \frac{3^{2015}-1}{2}$
R= $\frac{S*2}{3^{2015}-1}= \frac{ \frac{3^{2015}-1}{2}*2 }{3^{2015}-1} =1$