Question

calculati: S=1/2+1/6+1/12...1/90

Answer 1

Răspuns:

S= 1/1·2 + 1/2·3 + 1/3·4 +........+1/9·10 = (1/1 - 1/2) + (1/2 - 1/3) + (1/3 -1/4) + ......+ (1/9 - 1/10) = 1/1 - 1/10 = 9/10

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