Question

Dada a P.A (5, 10, 15) determine a soma dos 30 primeiros termos

Answer 1

a30=5+(30-1).5
a30=5+29.5
a30=5+145
a39=150

sn=(5+150).30/2
sn=155.30/2
sn=4.650/2
sn=2.325