Question

*di ketahui barisan
3, 15, 75
Tentukan
a). Suku ke 5
b). Jumlah 7 suku pertama

Answer 1

A) U5 = a.r⁴
= 3.5⁴
= 3.625
= 1875

b) S7 = a(r^7 -1)/(r-1)
= 3(5^7 -1)/(5-1)
= 3(78125-1)/4
= 3(78124)/4
= 58593