Calculate the sum of the first six terms of a geometric series with first term 2 and common ratio 3.(1 point)

Responses

242
242

728
728

186
186

364

1 answer

To calculate the sum of the first six terms of a geometric series, you can use the formula for the sum of the first \( n \) terms:

\[ S_n = a \frac{1 - r^n}{1 - r} \]

where:

  • \( S_n \) is the sum of the first \( n \) terms,
  • \( a \) is the first term,
  • \( r \) is the common ratio,
  • \( n \) is the number of terms.

In this case:

  • \( a = 2 \),
  • \( r = 3 \),
  • \( n = 6 \).

Now plug in the values:

\[ S_6 = 2 \frac{1 - 3^6}{1 - 3} \]

Calculating \( 3^6 \):

\[ 3^6 = 729 \]

Now substitute this back in:

\[ S_6 = 2 \frac{1 - 729}{1 - 3} = 2 \frac{1 - 729}{-2} = 2 \frac{-728}{-2} \]

Simplifying:

\[ S_6 = 2 \cdot 364 = 728 \]

So, the sum of the first six terms of the geometric series is 728.