Question

1+3+5+7+...+2001+2003

Answer 1

Răspuns:

Explicație pas cu pas:

=1+2+3+4+..+2002+2003-2-4-..-2002

=1+2+3+..+2003-2 (1+2+3+..+1001)

=2003×2004/2-2×(1001×1002/2)

=2003×1002-1001×1002

=1002×(2003-1001)

=1002×1002=1002^2

1+2+3+....+n=n (n+1)/2