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In Exercises \(12-15\), write the first 5 terms of the sequence \(a_{n}=f(n)\) $$ f(n)=\frac{n(n-1)}{2} $$

Short Answer

Expert verified
Answer: The first 5 terms of the sequence are 0, 1, 3, 6, 10.

Step by step solution

01

Write the first term of the sequence (n=1)

To find the first term of the sequence, we plug in n=1 into the given function: $$ a_1 = f(1) = \frac{1(1-1)}{2} = \frac{1(0)}{2} = 0 $$
02

Write the second term of the sequence (n=2)

To find the second term of the sequence, we plug in n=2 into the given function: $$ a_2 = f(2) = \frac{2(2-1)}{2} = \frac{2(1)}{2} = 1 $$
03

Write the third term of the sequence (n=3)

To find the third term of the sequence, we plug in n=3 into the given function: $$ a_3 = f(3) = \frac{3(3-1)}{2} = \frac{3(2)}{2} = 3 $$
04

Write the fourth term of the sequence (n=4)

To find the fourth term of the sequence, we plug in n=4 into the given function: $$ a_4 = f(4) = \frac{4(4-1)}{2} = \frac{4(3)}{2} = 6 $$
05

Write the fifth term of the sequence (n=5)

To find the fifth term of the sequence, we plug in n=5 into the given function: $$ a_5 = f(5) = \frac{5(5-1)}{2} = \frac{5(4)}{2} = 10 $$ Finally, the first 5 terms of the sequence \(a_n=f(n)=\frac{n(n-1)}{2}\) are: 0, 1, 3, 6, 10.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Sequence
A sequence is an ordered list of numbers that follow a certain pattern or rule. Each number in the sequence is called a term, and the set of terms is usually generated by a specific function. In mathematics, sequences are a fundamental concept because they allow us to describe patterns and predict future outcomes based on the rule applied to generate the sequence.
For example, consider the sequence generated by the function \(f(n) = \frac{n(n-1)}{2}\). This sequence includes the first few terms as 0, 1, 3, 6, 10, and continues further as more terms are calculated by increasing \(n\). The sequence demonstrates a systematic way of capturing the output of this function as applied sequentially.
Sequences can be finite or infinite, depending largely on whether there is a defined ending point to the pattern or whether it keeps going indefinitely.
Term of a sequence
A term of a sequence is a specific element or item in that sequence. It is typically represented by symbols such as \(a_n\), where \(n\) indicates the position of the term in the sequence. Understanding the position of a term is crucial because it directly relates to the function or rule used to generate the sequence.
To calculate any term in the given sequence, you apply the function \(f(n)\) at different values of \(n\). For instance:
  • First term \(a_1\): Calculated by setting \(n = 1\), resulting in \(a_1 = \frac{1(1-1)}{2} = 0\).
  • Second term \(a_2\): Set \(n = 2\), resulting in \(a_2 = \frac{2(2-1)}{2} = 1\).
  • Higher terms follow similarly, providing values at each position depending on \(n\).
Each term builds on the previous terms and reflects a unique value generated by the function when the sequence rule is applied.
Mathematical function
A mathematical function describes a relationship between a set of inputs and outputs, where each input is associated with exactly one output. Functions are a cornerstone in mathematics because they provide a systematic way to model the world around us.
In the context of the given sequence, the function \(f(n) = \frac{n(n-1)}{2}\) is used to determine each term by changing the input \(n\). This particular function showcases how mathematical functions can produce interesting number patterns, often seen in arithmetic or geometric sequences.
To utilize a mathematical function in sequences, follow these steps:
  • Identify the function rule which describes how each term is formed.
  • Apply the rule by replacing \(n\) with the desired number to get the corresponding term.
  • Repeat this process to generate more terms when needed.
Through the careful application of function rules, sequences help us explore and understand diverse mathematical concepts efficiently.

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