Question

Jika diketahui dari suatu deret geometri s=4 1/2 dan r= 1/3 jadi suku pertamanya berapa

Answer 1

Answer 2

S4 = a(1 - r^4) / (1 - r)
1/2 = a (1 - (1/3)^4) / (1 - 1/3)
1/2 = a ( 1 - 1/81) / (2/3)
1/2 x 2/3 = a (80/81)
1/3 = a ( 80/81)
1/3 : 80/81 = a
1/3 x 81 /80 = a
a = 27/80
U1 = 27/80