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Find the sum of the first 8 terms of the following series, to the nearest integer.

3, 9/4 27/16 ,...

User SAPLogix
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1 Answer

6 votes

Answer:

The given series is a geometric series with a common ratio of \( \frac{3}{4} \) because each term is obtained by multiplying the previous term by \( \frac{3}{4} \).

The general form of a geometric series is \( a + ar + ar^2 + \ldots + ar^{n-1} \), where:

- \( a \) is the first term,

- \( r \) is the common ratio,

- \( n \) is the number of terms.

In this case:

- \( a = 3 \) (the first term),

- \( r = \frac{3}{4} \) (the common ratio),

- \( n = 8 \) (the number of terms).

The sum of the first \( n \) terms of a geometric series is given by the formula \( S_n = \frac{a(1 - r^n)}{1 - r} \).

Let's calculate it for the given series:

\[ S_8 = \frac{3(1 - \left(\frac{3}{4}\right)^8)}{1 - \frac{3}{4}} \]

\[ S_8 = \frac{3(1 - \frac{6561}{65536})}{\frac{1}{4}} \]

\[ S_8 = \frac{3(\frac{58975}{65536})}{\frac{1}{4}} \]

\[ S_8 = \frac{176925}{8192} \]

Now, to the nearest integer, \( S_8 \approx 22 \).

So, the sum of the first 8 terms of the given series is approximately 22 (rounded to the nearest integer).

User Akshat Goel
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