Question

qual a soma da pa (-30; -21; -12;...231) ???​

Answer 1

(n-1) = an-a1/r

n-1 = 231+30/9

n-1 = 261/9

n-1 = 29

n = 30

s=(a1+an).n/2

s=(-30+231).30/2

s=(201).15

s= 3015