Jumlah n suku pertama deret log 3+log 9+ log 27...adaah

jawab

log 3 + log 9 + log 27 +...
log 3+ 2. log 3 + 3.log 3+ ...+n.log 3

sn = n/2 ( log 3 + n.log 3)
sn = n/2 ( log 3)(n +1)
sn = n/2(n+1) . log 3
sn = 1/2 (n)(n+1)(log 3)