Math Problem Statement

g2=24,r=1/2 find expression for gn and use it for g5 (geometric sequence)

Solution

In a geometric sequence, the general term gng_n is given by the formula:

gn=g1rn1g_n = g_1 \cdot r^{n-1}

Here:

  • g2=24g_2 = 24 (second term),
  • r=12r = \frac{1}{2} (common ratio).

Step 1: Find g1g_1

Using the formula for the second term:

g2=g1r21g_2 = g_1 \cdot r^{2-1}

Substitute g2=24g_2 = 24 and r=12r = \frac{1}{2}:

24=g11224 = g_1 \cdot \frac{1}{2}

Multiply both sides by 2:

g1=48g_1 = 48

Step 2: Write the general expression for gng_n

Now that we know g1=48g_1 = 48, substitute it into the general formula:

gn=48(12)n1g_n = 48 \cdot \left(\frac{1}{2}\right)^{n-1}

Step 3: Find g5g_5

Substitute n=5n = 5 into the formula:

g5=48(12)51g_5 = 48 \cdot \left(\frac{1}{2}\right)^{5-1}

g5=48(12)4g_5 = 48 \cdot \left(\frac{1}{2}\right)^4

g5=48116g_5 = 48 \cdot \frac{1}{16}

g5=3g_5 = 3

Final Results:

  1. General expression for gng_n: gn=48(12)n1g_n = 48 \cdot \left(\frac{1}{2}\right)^{n-1}

  2. Value of g5g_5: g5=3g_5 = 3

Would you like further clarification or details?


Here are 5 related questions to consider:

  1. What is the sum of the first nn terms of a geometric sequence?
  2. How does the common ratio affect the behavior of a geometric sequence?
  3. Can you derive the nth term for a geometric sequence with a negative common ratio?
  4. What happens to gng_n as nn \to \infty in this sequence?
  5. How do you determine if a sequence is geometric based on a given set of terms?

Tip: Always double-check your calculations, especially when working with exponents and fractions!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Geometric Sequences
Exponents
Algebra

Formulas

General term of a geometric sequence: gn = g1 * r^(n-1)

Theorems

Geometric Sequence Formula

Suitable Grade Level

Grades 8-10