Question

1+3+5+...+2009+2011 si 1+3+5+...1003+1005
va rog raspundeti urgent!!

Answer 1

1+3+5+...+2n+1=(n+1)²
1+3+5+...+2x1005+1=(1005+1)²=1006²=1012036
1+3+5+...+2x502+1=(502+1)²=503²=253009

Answer 2

1+(1+2x1)+(1+2x2)+...+(1+2x1004)+(1+2x1005)
1x1006=1006
1006+2(1+2+...+1005)
Suma primelor 1005 nr. naturale.
1+2+...+1005=1005x1006:2=503x1005=505 515
2x505 515+1006=1 012 036