Math Problem Statement

Given the sequence -14, -6, -2, 0, 1, ..., find the recursive formula.

Solution

To find the recursive formula for the given sequence 14,6,2,0,1,-14, -6, -2, 0, 1, \dots, we need to determine how each term relates to the previous term.

First, let's look at the differences between consecutive terms:

6(14)=8-6 - (-14) = 8 2(6)=4-2 - (-6) = 4 0(2)=20 - (-2) = 2 10=11 - 0 = 1

Notice that the differences between consecutive terms are decreasing: 88, 44, 22, 11, \dots.

The first difference itself forms a sequence, which seems to be halving each time.

Thus, the recursive formula can be expressed as follows:

  1. Let the sequence be denoted by ana_n.
  2. Define the difference between consecutive terms as dn=an+1and_n = a_{n+1} - a_n.

Given the observations, we have: d1=8,d2=4,d3=2,d4=1,d_1 = 8, \, d_2 = 4, \, d_3 = 2, \, d_4 = 1, \dots The difference between consecutive terms dnd_n follows: dn+1=dn2d_{n+1} = \frac{d_n}{2} Starting with d1=8d_1 = 8.

So, the recursive formula for the sequence ana_n can be written as: an+1=an+dnwheredn+1=dn2, with d1=8a_{n+1} = a_n + d_n \quad \text{where} \quad d_{n+1} = \frac{d_n}{2}, \text{ with } d_1 = 8

Thus, we have a recursive system:

a_{n+1} = a_n + d_n \\ d_{n+1} = \frac{d_n}{2} \end{cases}$$ with initial conditions: $$a_1 = -14, \, d_1 = 8$$ Would you like further details on how to derive a closed-form expression, or do you have any other questions? --- Here are some related questions to explore: 1. How would you find the explicit formula for this sequence? 2. What happens to the sequence as $$n$$ becomes very large? 3. Can you describe how to solve a similar problem with different initial values? 4. How does the nature of the recursive difference $$d_n$$ influence the sequence? 5. What if the differences $$d_n$$ decreased by a constant factor other than $$\frac{1}{2}$$? 6. What would happen if the initial term was positive? 7. Can you generalize the pattern of differences to any sequence? 8. What other sequences might have similar recursive relations? **Tip:** When working with sequences, always check both the initial conditions and how the differences between terms evolve. This often provides insight into the nature of the sequence.

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Math Problem Analysis

Mathematical Concepts

Sequences
Recursive Formulas
Arithmetic Sequences

Formulas

Recursive formula for arithmetic sequences

Theorems

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Suitable Grade Level

High School