Math Problem Statement

Find the 8th term of the series 1/8, 1/4, 1/2 ..

Solution

The given series is:

18,14,12,\frac{1}{8}, \frac{1}{4}, \frac{1}{2}, \ldots

This is a geometric progression (GP) because each term is obtained by multiplying the previous term by a constant ratio. Let's identify the first term (aa) and the common ratio (rr):

  • First term (aa) = 18\frac{1}{8}
  • Common ratio (rr) = 1418=2\frac{\frac{1}{4}}{\frac{1}{8}} = 2

The general formula for the nn-th term of a geometric progression is:

Tn=arn1T_n = a \cdot r^{n-1}

We are looking for the 8th term (T8T_8):

T8=18281=1827=18128=1288=16T_8 = \frac{1}{8} \cdot 2^{8-1} = \frac{1}{8} \cdot 2^7 = \frac{1}{8} \cdot 128 = \frac{128}{8} = 16

Thus, the 8th term of the series is 16.

Would you like further details on this?

Here are 5 related questions for practice:

  1. What is the 10th term of the same series?
  2. What is the sum of the first 8 terms of this series?
  3. Can you find the common ratio in a different way?
  4. What would the first negative term be in this GP if extended?
  5. How does the sum of infinite terms of a geometric series work?

Tip: In a geometric progression, knowing the first term and the common ratio allows you to calculate any term easily with the formula Tn=arn1T_n = a \cdot r^{n-1}.

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Math Problem Analysis

Mathematical Concepts

Algebra
Geometric Progression
Sequences

Formulas

T_n = a * r^(n-1)
Geometric progression nth term formula

Theorems

Geometric progression (GP) theorem

Suitable Grade Level

Grades 9-10