Question

Suku pertama deret geometri adalah 8, rasio 3, dan suku ke-n 5.832. tentukan n dan jumlah n suku pertamanya ?
Pakai cara ya... :)

Mohon bantuannya

Answer 1

A = 8
r = 3

un = ar^(n-1)
5.832 = 8 x 3^(n-1)
729 = 3^(n-1)
3^6 = 3^(n-1)
6 = n-1
n = 6+1
n = 7

S7 = a( r-1) / (r-1)
      = 8( 3^7-1) / (3-1)
      = 8 (2.187-1) /2
     = 4 (2.186)
    = 8.744

Answer 2

A = 8
r = 3

un = ar^(n-1)
5.832 = 8 x 3^(n-1)
729 = 3^(n-1)
3^6 = 3^(n-1)
6 = n-1
n = 6+1
n = 7

S7 = a( r-1) / (r-1)
      = 8( 3^7-1) / (3-1)
      = 8 (2.187-1) /2
     = 4 (2.186)
    = 8.744