jumlah 50 suku pertama deret log5 +log 55 + log 605 + log 6655 adalah...

a = log 5
b = log 55 - log 5 = log (55/5) = log 11
log 605 - log 55 = log (605/55) = log 11
Ini termasuk deret aritmatika, karena bedanya sama

U50 = a + 49b
= log5 + 49 (log11)
= log5 + log 11^49
= Log (5 x 11^49)
Sn = (n / 2)(a + Un)
S50 = 25(log5 + log(5 x 11^49))
= 25log5²(11^49)

Deret bentuk logaritma

log 5 + log 5(11) + log (5.11²)+ ...+log (5.11⁴⁹)
= log {5⁵⁰. 11⁴⁹)
= 50. 49. log (5.11)
= 2.450. log 55