Question

calcule a soma dos 35 primeiroa termos da pa 3 6 9 12

Answer 1

PA(3,6,9,12,...)

a1=3
r=6-3=3

a35=a1+(n-1).r
a35=3+(35-1).3
a35=3+34.3
a35=3+102
a35=105

S35=(3+105).35/2
S35=108.35/2
S35=3780/2
S35=1890