Question

Calcule a soma dos primeiros 500 termos da sequência (2,4,6,...,1000)

Answer 1

a1=2

r=2

a500=2+(500-1)*2 =1000

Sn=(a1+an)*n/2

S500=(2+1000)*500/2 =250.500

Answer 2

$S_{500} = \frac{ ( 2 + 1000 ) . 500}{2}$
$S_{500} =  (1002) . 250$
$S_{500} =  250500$