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1/2+1/2^2+1/2^3+...+1/2^2017
va roggg


Răspuns :

S=1/2+1/2 la2+1/2 la3+....+1/2 la 2016+.1/2 la2017. 2S=1+1/2+1/2 la2+.....1/2 la 2016 =>2S-S=1+1/2+1/2 la2+1/2 la2016-1/2-1/2 la2-1/2 la3-.....-1/2 la 2016 -1/2 la 2017=> S=1-1/2 la 2017