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Calculati
47+49+51+53+....+975


Răspuns :

Gauss 1+3+5..+2n-1=n²
47+49+51+53+....+975=
=(1+3+5+..+45+47+49+...975)-(1+3+...+45)
975=2n-1=>2n=976=>n=488
45=2n-1=>2n=46=>n=23
=488
²-23²
=238144-2025
=236119