Question

A soma dos termos da PA (-16,-14,-12,...,84)

Answer 1

a1=-16
an=84
r=a2-a1=-14-(-16)=-14+16=2

an=a1+(n-1).r
84=-16+(n-1).2
84=-16+2n-2
84+16+2=2n
2n=102
n=102/2
n=51

Sn=(a1+an).n/2
S51=(-16+84).51/2
S51=68.51/2
S51=34.51
S51=1734

A soma é igual a 1734.