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a fost răspuns

Aratati ca numarul 1997 + 2 x (1+2+......+1996) este patrat perfect

Răspuns :

1997+2x1996x(1996+1):2=1997+2x1996x1997:2=1997+2•998•1997=1997+2•1992236=1997+3984472=3986469
Luckyjr
1+2......1996=(1+1996)·1996:2
1997+2·1997·1996:2=1997+1997·1996,=1997(1+1996)=1997^2