Question

Aratati ca nr N egal 2011 + 2 (1+2+3+....+2010) este patrat perfect

Answer 1

$N=2011+2(1+2+3+...+2010)=2011+\frac{2*2010*2011}{2}=2011+2010*2011=2011(2010+1)=2011*2011=2011^2 - este \ patrat \ perfect$

Answer 2

2011 + 2 (1+2+3+....+2010) = 2011 +2* ( 2010*2011/2 ) = 2011+2* 1005*2011= 2011+ 2011*2010 = 2011( 1+ 2010) = 2011*2011= 2011^2 patrat perfect