Question

OBTENHA A SOMA DOS 51 PRIMEIROS TERMOS DA p.a (-15,-11,-7,-3,1,...)

Answer 1

an=a1+(n-1).r
an=-15+(51-1).4
an=-15+50.4
an=-15+200
an= 185

- Soma da P.A=

sn=(a1+an).n$sn=\frac{(a1+an).n}{2}$
$Sn=\frac{(-15+185).51}{2}$$Sn=\frac{170.51}{2}$$Sn= \frac{8670}{2}$$sn=4335$