# Thread: Sequences and Series questions

1. ## Sequences and Series questions

1. Find the sums of these AP's who's terms are logarithms

a) log (b) 36 + log (b) 18 + log (b) 9 + ...log (b) 9/8

b) log (x) 27/8 + log (x) 9/4 + log (x) 3/2 + ....(10 terms)

2. ## Re: Sequences and Series questions

For a), note that the term inside the logarithm is halved each time.

So, rewrite it as

$\log_b 36 + \log_b \left(36\cdot \frac 1 2\right) + \log_b \left(36\cdot \frac 1 2 \cdot \frac 1 2\right) + ...$

And use the law $\log ab = \log a + \log b$.

b) can be solved similarly.

3. ## Re: Sequences and Series questions

Thats actually a good question (at least for me)

It took me long to realise the ratio and AP being together, fan96 gets the credit

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