Răspuns:
Explicație pas cu pas:
a = 1 + 1/2 + 1/2^2 + 1/2^3 + 1/2^4 + 1/2^5
a*1/2 = 1/2 + 1/2^2 + 1/2^3 + 1/2^4 + 1/2^5 + 1/2^6
a - a*1/2 = 1/2 + 1/2^2 + 1/2^3 + 1/2^4 + 1/2^5 + 1/2^6 - 1 - 1/2 - 1/2^2 - 1/2^3 - 1/2^4 - 1/2^5 = 1/2^6 - 1
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a - a*1/2 = 1/2^6 - 1
a/2 = 1/2^6 - 1
a = 2*(1/2^6 - 1) = 1/2^5 - 2
