Math Problem Statement

Here is the recursive definition of a sequence: f(1) = 10, f(n) = f(n-1) - 1.5 for n ≥ 2. a. Is this sequence arithmetic, geometric, or neither? b. List at least the first five terms of the sequence.

Solution

The problem you're working on presents a recursive sequence defined as follows:

f(1)=10,f(n)=f(n1)1.5 for n2.f(1) = 10, \quad f(n) = f(n-1) - 1.5 \text{ for } n \geq 2.

Let's break this down:

Part (a)

Is this sequence arithmetic, geometric, or neither?

An arithmetic sequence has a constant difference between consecutive terms. The recursive formula f(n)=f(n1)1.5f(n) = f(n-1) - 1.5 subtracts 1.5 from the previous term each time, which indicates a constant difference of 1.5-1.5. Therefore, this is an arithmetic sequence.

Part (b)

List at least the first five terms of the sequence.

Using the recursive relation:

  • f(1)=10f(1) = 10
  • f(2)=f(1)1.5=101.5=8.5f(2) = f(1) - 1.5 = 10 - 1.5 = 8.5
  • f(3)=f(2)1.5=8.51.5=7f(3) = f(2) - 1.5 = 8.5 - 1.5 = 7
  • f(4)=f(3)1.5=71.5=5.5f(4) = f(3) - 1.5 = 7 - 1.5 = 5.5
  • f(5)=f(4)1.5=5.51.5=4f(5) = f(4) - 1.5 = 5.5 - 1.5 = 4

So, the first five terms of the sequence are: 10,8.5,7,5.5,4.10, 8.5, 7, 5.5, 4.

Let me know if you need further details or explanations!

Here are 5 related questions:

  1. How can we generalize the formula for any arithmetic sequence?
  2. What would the 10th term of this sequence be?
  3. How can we find the sum of the first nn terms of an arithmetic sequence?
  4. Can a recursive formula be used to represent geometric sequences as well?
  5. What are the applications of arithmetic sequences in real-world problems?

Tip: For arithmetic sequences, you can always use the formula an=a1+(n1)da_n = a_1 + (n-1)d, where dd is the common difference.

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Math Problem Analysis

Mathematical Concepts

Sequences
Arithmetic Sequences
Recursive Definitions

Formulas

f(n) = f(n-1) - 1.5
a_n = a_1 + (n-1)d

Theorems

Arithmetic Sequence Theorem

Suitable Grade Level

Grades 8-10