Math Problem Statement

The formula for the sum of a geometric series is shown.

Sn=a1(1−rn)1−r

A geometric series is shown.

 1, 3, 9, 27, ...

What is the value of S10 for this geometric series?

28

150

29,524

88,572

Solution

To find the sum of the first nn terms of a geometric series, we use the formula:

Sn=a11rn1rS_n = a_1 \frac{1 - r^n}{1 - r}

where:

  • SnS_n is the sum of the first nn terms,
  • a1a_1 is the first term,
  • rr is the common ratio,
  • nn is the number of terms.

For the series 1,3,9,27,1, 3, 9, 27, \ldots:

  • The first term a1=1a_1 = 1.
  • The common ratio r=31=3r = \frac{3}{1} = 3.

We need to find S10S_{10}, the sum of the first 10 terms.

S10=1131013=13102S_{10} = 1 \cdot \frac{1 - 3^{10}}{1 - 3} = \frac{1 - 3^{10}}{-2}

Calculating 3103^{10}:

310=590493^{10} = 59049

Now substitute it into the formula:

S10=1590492=590482=29524S_{10} = \frac{1 - 59049}{-2} = \frac{-59048}{-2} = 29524

So, the value of S10S_{10} for this geometric series is:

29,524

Would you like more details on this solution or have any questions?

Here are some related questions for further understanding:

  1. What is the formula for the sum of an infinite geometric series?
  2. How do you determine the common ratio in a geometric sequence?
  3. What is the sum of the first 5 terms of the series 1,3,9,27,1, 3, 9, 27, \ldots?
  4. How does the sum of a geometric series change when the common ratio is less than 1?
  5. How do you find the sum of a geometric series with a negative common ratio?

Tip: When using the geometric series sum formula, ensure the common ratio rr is not equal to 1, as the formula does not apply in such cases.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Algebra
Geometric Series
Exponents

Formulas

Sum of a geometric series: S_n = a_1 (1 - r^n) / (1 - r)

Theorems

Geometric series sum formula

Suitable Grade Level

Grades 8-10