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No 8) anggap aja log b = x log b² = 2x log b^9 = 9x berarti : log b + log b² + log b³ +....log b^9 = x + 2x +... +9x = 45x jadi 45x = 45 log b
jumlah 10 suku pertama = s10 = log a + (log a - log b) + (log a - log b²) + (log a - log b³) +...... = (log a + log a + log a +....u10) - (log b + log b² + log b³ +...) = 10 log a - 45 log b
anggap aja log b = x
log b² = 2x
log b^9 = 9x
berarti :
log b + log b² + log b³ +....log b^9 =
x + 2x +... +9x = 45x
jadi 45x = 45 log b
jumlah 10 suku pertama = s10 =
log a + (log a - log b) + (log a - log b²) + (log a - log b³) +...... =
(log a + log a + log a +....u10) - (log b + log b² + log b³ +...) =
10 log a - 45 log b