Question

buna seara,am nevoie dacă se poate cu rezolvarea ex.4, ambele subpuncte.
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Answer 1

Răspuns:

1/2^2 <1/1*2

1/3^2 <1/2*3

.....................

1/2011^2<1/2010*2011

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1/2^2+...+1/2^2011 <1/1*2+1/2*3+...+1/2010*2011<=>

<=>1/2^2+...+1/2^2011<(1/1-1/2) +(1/2 -1/3) +...+(1/2010-1/2011) <=>

<=>1/2^2+...+1/2^2011 <1/1 -1/2011 <=>

<=>1/2^2+...+1/2^2011<2010/2011 punctul B

Explicație pas cu pas: