Question

Calculati A=1/1×4+1/2×6+1/3×8+1/4×10+.......+1/48×98+1/49×100 VA ROG REPEDE SI PE FOAIE SI FACETI POZA APOI PLSSSSS DAU CORONITA

Answer 1

Salut!
1/(1x4) = 2/(2x4) = 1/2 - 1/4;
1/(2x6) = 2/(4x6) = 1/4 - 1/6;
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1/(49x100)_ = 2/(98x100) = 1/98 - 1/100;

Adunam aceste relatii matematice, una sub alta, si obtinem A = 1/2 - 1/100 = 49/100;
Bafta!