Math Problem Statement

Find the nth term of the sequence: -2, 4, -8, 16, -32

Solution

The sequence provided in the image is:
2,4,8,16,32-2, 4, -8, 16, -32

This is a geometric sequence because each term is obtained by multiplying the previous term by a constant ratio. Let's find the common ratio rr.

r=42=2r = \frac{4}{-2} = -2 r=84=2r = \frac{-8}{4} = -2 r=168=2r = \frac{16}{-8} = -2

So, the common ratio rr is 2-2.

The general formula for the nn-th term of a geometric sequence is: an=a1rn1a_n = a_1 \cdot r^{n-1} Where:

  • a1a_1 is the first term of the sequence.
  • rr is the common ratio.
  • nn is the term number.

Here, a1=2a_1 = -2 and r=2r = -2. Therefore, the formula for the nn-th term becomes: an=2(2)n1a_n = -2 \cdot (-2)^{n-1} Thus, the nn-th term of the sequence is: an=2(2)n1a_n = -2 \cdot (-2)^{n-1}

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

Related Questions:

  1. How do you determine whether a sequence is arithmetic or geometric?
  2. What happens if the common ratio in a geometric sequence is a fraction?
  3. Can a sequence have both positive and negative terms and still be geometric?
  4. How would the formula change if the first term were positive instead of negative?
  5. What is the sum of the first nn terms of a geometric sequence?

Tip:

In geometric sequences, the sign of the common ratio determines whether the sequence alternates between positive and negative values.

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Math Problem Analysis

Mathematical Concepts

Sequences
Geometric Sequences
Algebra

Formulas

General formula for nth term of geometric sequence: a_n = a_1 * r^(n-1)

Theorems

Properties of geometric sequences

Suitable Grade Level

Grades 9-12