Question

calcule a soma dos 34 primeiros termos da p.a 5,10, 15

Answer 1

an = 5 + (34 - 1).5
an = 5 + 33.5
an = 5 + 165
an = 170


Sn = (a1 + an).n/2


Sn = (5 + 170).34/2
Sn = 175.34/2
Sn = 5950/2
Sn = 2975

Answer 2

An = a1 + ( n - 1 ) x r
A34 = 5 + (34 - 1) x 5
A34 = 5 + 33 x 5
A34 = 5 + 165
A34 = 170

SN = (a1 + an) x n/2
SN = (5 + 170) x 34/2
SN = 175 x 34/2
SN = 2975