Adapt the formula 1 + 2 + 3 + ... + (n − 1) + n = nx(n+1) 2 a polynomial in terms of n and in terms of a triangular number. 1) S(n) = 4+5+6+...+n+ (n + 1). TO=1+2+3+ intc^tis-1-2-3 =1+2+3+1 = (n +D(~+2) 60 2 to find the following sums. Represent the answe ·le

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
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Is number 1 correct? If not can you help me with it?
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### Educational Mathematics Quiz

#### Course: MATH 641
**Take-Home Quiz 1.01b**
**Name:** Patrice Walker  
**Points:** 12  
**Total Score:** 5 / 12

---

**Directions:**

1. Show complete work to earn appropriate credit.
2. You may check your answers with a classmate.
3. Solve each problem in the space provided.

---

**Problem 1:**

Adapt the formula \(1 + 2 + 3 + \ldots + (n-1) + n = \frac{n \times (n+1)}{2}\) to find the following sums. Represent the answers as a polynomial in terms of \(n\) in terms of a triangular number.

**Solution:**

\[ S(n) = 4 + 5 + 6 + \ldots + n + (n+1) \]

Steps to solve:

\[
\begin{aligned}
&= (1 + 2 + 3 + \ldots + (n+1)) - (1 + 2 + 3) \\
&= \frac{(n+1)(n+2)}{2} - 6 \\
&= \frac{n^2 + 3n + 2}{2} - 6 \\
&= \frac{n^2 + 3n + 2 - 12}{2} \\
&= \frac{n^2 + 3n - 10}{2} \\
\end{aligned}
\]

Thus,

\[ S(n) = \frac{n^2 + 3n - 10}{2} \]

**Problem 2:**

\[ D(n) = (n-3) + (n-3) + (n-4) + (n-5) + \ldots + 3 + 2 + 1 \]

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Note: Ensure to review the steps above, and check each calculation for accuracy. Collaboration with classmates is encouraged, but the representation of your individual understanding is essential.

---
Transcribed Image Text:--- ### Educational Mathematics Quiz #### Course: MATH 641 **Take-Home Quiz 1.01b** **Name:** Patrice Walker **Points:** 12 **Total Score:** 5 / 12 --- **Directions:** 1. Show complete work to earn appropriate credit. 2. You may check your answers with a classmate. 3. Solve each problem in the space provided. --- **Problem 1:** Adapt the formula \(1 + 2 + 3 + \ldots + (n-1) + n = \frac{n \times (n+1)}{2}\) to find the following sums. Represent the answers as a polynomial in terms of \(n\) in terms of a triangular number. **Solution:** \[ S(n) = 4 + 5 + 6 + \ldots + n + (n+1) \] Steps to solve: \[ \begin{aligned} &= (1 + 2 + 3 + \ldots + (n+1)) - (1 + 2 + 3) \\ &= \frac{(n+1)(n+2)}{2} - 6 \\ &= \frac{n^2 + 3n + 2}{2} - 6 \\ &= \frac{n^2 + 3n + 2 - 12}{2} \\ &= \frac{n^2 + 3n - 10}{2} \\ \end{aligned} \] Thus, \[ S(n) = \frac{n^2 + 3n - 10}{2} \] **Problem 2:** \[ D(n) = (n-3) + (n-3) + (n-4) + (n-5) + \ldots + 3 + 2 + 1 \] --- Note: Ensure to review the steps above, and check each calculation for accuracy. Collaboration with classmates is encouraged, but the representation of your individual understanding is essential. ---
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