Question

Qual é a Soma dos termos da PA ( 3, 7, 11, 15, 19, 23, 27, 31, 35, 39) ?

Answer 1

Sn= [(a1 + an) . n]÷2
SN= [ (3+39) . 10]÷2
SN= [ 420 ] ÷2
SN= 210

Answer 2

Sn= [(a1 + an) . n]/2

Sn= [ (3+39) . 10]/2
Sn= [ 420 ]/2
Sn= 210