Question

В геометрической прогрессии a1=3, q=1/3

Answer 1

а1=3;q=1/3
a(n)=a1•q^(n-1)=3•(1/3)^(n-1)
S(n)=(a1•q^n-1)/(q-1)=(3•(1/3)^n-1)/(1/3-1)=
(3•(1/3)^n-1)/(-2/3)
S=a1/(q-1)=3/(-2/3)=-3•3/2=-9/2=-4,5
(|q|<1)