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NNoi2
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Va rog este urgent: (2+4+...............2012)-(1+3+............2011) , (22+44+.........2024):(11+22......2012)

Răspuns :

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(2+4+...............2012)-(1+3+............2011)=2(1+2+...+1006)-[(2·0+1)+(2·1+1)+(2·2+1)+...+(2·1005+1)]=
=2·1007·1006/2-[2(1+2+...+1005)+1006]=
=1007·1006-(1006·1005+1006)=
=1007·1006-1006(1005+1)=
=1007·1006-1006·1006=
=1006(1007-1006)=
=1006

(22+44+.........4024):(11+22......2012)=
=2(11+22+.....+2012)/(11+22+..+2012)=
=2

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