Given the recursive sequence ak = (12-06-1) ² - 1 ak-1 -k² + 1 for all k ≥ 1, and a₁ = -4, find a₂ and as-

Intermediate Algebra
19th Edition
ISBN:9780998625720
Author:Lynn Marecek
Publisher:Lynn Marecek
Chapter12: Sequences, Series And Binomial Theorem
Section: Chapter Questions
Problem 328PT: Find the first term and common difference of an arithmetic sequence whose ninth term is -1 and the...
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### Educational Exercise: Recursive Sequences and Summation

**Instructions:**
Find the following. **SHOW AND JUSTIFY YOUR WORK.**

#### (a) Recursive Sequence Calculation
Given the recursive sequence \( a_k = \left(\frac{1}{2} a_{k-1}\right)^2 - k^2 + 1 \) for all \( k \geq 1 \), and \( a_1 = -4 \), find \( a_2 \) and \( a_3 \).

#### (b) Summation Problems
Compute the following sums using formulas from class. **Do not try to compute something like \(2^{24}\). You may leave your answer in terms of big numbers like this.**

**i.** \(-23 + (-23)^2 + (-23)^3 + \cdots + (-23)^{11}\)

**ii.** \(6 + 12 + 18 + 24 + 30 + \cdots + 1200\)

### Solution Outline:

#### (a) Solving the Recursive Sequence
1. **Find \( a_2 \):**
   - Use the given formula with \( k = 2 \).
  
2. **Find \( a_3 \):**
   - Use the same formula with \( k = 3 \), after calculating \( a_2 \).

#### (b) Summation Problems
1. **i. Sum of Powers of \(-23\):**
   - Recognize that this is a geometric series with \( a = -23 \) and \( r = -23 \).

2. **ii. Sum of Arithmetic Series:**
   - Identify \( a = 6 \) (first term), \( l = 1200 \) (last term), and common difference \( d = 6 \).

### Detailed Solution Steps
- **Recursive Sequence Calculation (a):**
  1. **Find \( a_2 \):**
     \[
     a_2 = \left( \frac{1}{2} a_1 \right)^2 - 2^2 + 1 = \left( \frac{1}{2} \times -4 \right)^2 - 4 + 1 = 4 - 4 + 1 = 1
     \]

  2. **Find \( a_3 \):**
     \[
     a_3 = \
Transcribed Image Text:### Educational Exercise: Recursive Sequences and Summation **Instructions:** Find the following. **SHOW AND JUSTIFY YOUR WORK.** #### (a) Recursive Sequence Calculation Given the recursive sequence \( a_k = \left(\frac{1}{2} a_{k-1}\right)^2 - k^2 + 1 \) for all \( k \geq 1 \), and \( a_1 = -4 \), find \( a_2 \) and \( a_3 \). #### (b) Summation Problems Compute the following sums using formulas from class. **Do not try to compute something like \(2^{24}\). You may leave your answer in terms of big numbers like this.** **i.** \(-23 + (-23)^2 + (-23)^3 + \cdots + (-23)^{11}\) **ii.** \(6 + 12 + 18 + 24 + 30 + \cdots + 1200\) ### Solution Outline: #### (a) Solving the Recursive Sequence 1. **Find \( a_2 \):** - Use the given formula with \( k = 2 \). 2. **Find \( a_3 \):** - Use the same formula with \( k = 3 \), after calculating \( a_2 \). #### (b) Summation Problems 1. **i. Sum of Powers of \(-23\):** - Recognize that this is a geometric series with \( a = -23 \) and \( r = -23 \). 2. **ii. Sum of Arithmetic Series:** - Identify \( a = 6 \) (first term), \( l = 1200 \) (last term), and common difference \( d = 6 \). ### Detailed Solution Steps - **Recursive Sequence Calculation (a):** 1. **Find \( a_2 \):** \[ a_2 = \left( \frac{1}{2} a_1 \right)^2 - 2^2 + 1 = \left( \frac{1}{2} \times -4 \right)^2 - 4 + 1 = 4 - 4 + 1 = 1 \] 2. **Find \( a_3 \):** \[ a_3 = \
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