Math Problem Statement

Find the sum of the firstcn terms of the geometric sequence. n=6, a1=2, r=4

Solution

To find the sum of the first nn terms of a geometric sequence, you can use the formula:

Sn=a1(rn1)r1S_n = \frac{a_1 \cdot (r^n - 1)}{r - 1}

Given:

  • n=6n = 6
  • a1=2a_1 = 2
  • r=4r = 4

Now, plug in the values:

S6=2(461)41S_6 = \frac{2 \cdot (4^6 - 1)}{4 - 1}

First, calculate 464^6:

46=40964^6 = 4096

Then:

S6=2(40961)3=240953=81903=2730S_6 = \frac{2 \cdot (4096 - 1)}{3} = \frac{2 \cdot 4095}{3} = \frac{8190}{3} = 2730

So, the sum of the first 6 terms of the geometric sequence is 2730.

Would you like more details or have any questions?

Here are five related questions to consider:

  1. How does the sum formula change if the common ratio rr is 1?
  2. What is the sum of the first 10 terms for this sequence?
  3. How would you find the sum of an infinite geometric series?
  4. How does the sum change if rr is a fraction between 0 and 1?
  5. Can you derive the sum formula for a geometric sequence?

Tip: The sum of the first nn terms in a geometric sequence grows rapidly if the common ratio rr is greater than 1.

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Math Problem Analysis

Mathematical Concepts

Geometric Sequence
Summation of Series

Formulas

Sum of a geometric series formula: Sn = a1 * (r^n - 1) / (r - 1)

Theorems

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Suitable Grade Level

Grades 10-12