Question

Determine a soma do termos tem a P.G.(8, 24, 72, ..., 52488)​

Answer 1

Resposta:Sn=78728

Explicação passo a passo:

an=52488,a1=8,q=a2/a1--->q=24/8--->q=3,,n=?,Sn=?

Sn=an.q-a1/q-1

Sn=52488.3-8/3-1

Sn=157464-8/2

Sn=157456/2

Sn=78728

  ou

an=a1.q^n-1                    Sn=a1.[(q^n)-1]/q-1

52488=8.3^n-1              S9=8.[(3^9)-1]/3-1

52488/8=3^n-1              S9=8.[19683-1]/2

6561=3^n-1                     S9=4.19682

3^8=3^n-1                       S9=78728

8=n-1

n=8+1

n=9