Chapter 12: Problem 8
Find the first four terms and the 100th term of the sequence. $$a_{n}=\frac{1}{n^{2}}$$
Short Answer
Expert verified
First four terms are 1, \( \frac{1}{4} \), \( \frac{1}{9} \), \( \frac{1}{16} \); 100th term is \( \frac{1}{10000} \).
Step by step solution
01
Understand the Sequence Formula
The sequence is defined by the formula \( a_n = \frac{1}{n^2} \). This means the nth term of the sequence is the reciprocal of the square of \( n \).
02
Calculate the First Term
Substitute \( n = 1 \) into the formula: \[a_1 = \frac{1}{1^2} = 1\]So, the first term \( a_1 \) is 1.
03
Calculate the Second Term
Substitute \( n = 2 \) into the formula: \[a_2 = \frac{1}{2^2} = \frac{1}{4}\]So, the second term \( a_2 \) is \( \frac{1}{4} \).
04
Calculate the Third Term
Substitute \( n = 3 \) into the formula: \[a_3 = \frac{1}{3^2} = \frac{1}{9}\]So, the third term \( a_3 \) is \( \frac{1}{9} \).
05
Calculate the Fourth Term
Substitute \( n = 4 \) into the formula: \[a_4 = \frac{1}{4^2} = \frac{1}{16}\]So, the fourth term \( a_4 \) is \( \frac{1}{16} \).
06
Calculate the 100th Term
Substitute \( n = 100 \) into the formula: \[a_{100} = \frac{1}{100^2} = \frac{1}{10000}\]So, the 100th term \( a_{100} \) is \( \frac{1}{10000} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding the Sequence Formula
A sequence formula act as a blueprint in mathematics to determine each term of a sequence. In this exercise, the sequence formula is given by \(a_n = \frac{1}{n^2}\). Here, \(n\) is a positive integer, which denotes the position of a term in the sequence. This formula effectively tells us that each term, \(a_n\), is calculated by taking the reciprocal of the square of \(n\).
- Sequential formulas help in predicting terms without listing them all.
- They are crucial for identifying patterns in sequences.
The Concept of Reciprocal
The term "reciprocal" refers to the inverse of a number. Basically, if you have a number \(x\), its reciprocal is \(\frac{1}{x}\). For any non-zero real number, multiplying it by its reciprocal always results in 1.
In our sequence formula, \(\frac{1}{n^2}\) uses the reciprocal of the square of \(n\), meaning we're flipping the fraction. Hence:
In our sequence formula, \(\frac{1}{n^2}\) uses the reciprocal of the square of \(n\), meaning we're flipping the fraction. Hence:
- For \(n = 1\), the reciprocal of \(1^2\) is \(\frac{1}{1} = 1\).
- For \(n = 2\), the reciprocal of \(4\) is \(\frac{1}{4}\).
- For \(n = 3\), the reciprocal of \(9\) is \(\frac{1}{9}\).
Understanding the Square of a Number
Squaring is an arithmetic operation where a number is multiplied by itself. For instance, the square of \(n\) is given by \(n^2 = n \times n\). Squaring results in a positive number because:
- negative times negative yields positive, as seen when squaring negative numbers.
- \(n = 1\), \(1^2 = 1\)
- \(n = 2\), \(2^2 = 4\)
- \(n = 3\), \(3^2 = 9\)
What Are Terms of a Sequence?
In mathematics, a sequence is an ordered set of numbers, and each of these numbers is called a term. Terms occupy specific positions in a sequence and are typically designated by \(a_n\), where \(n\) is an index representing the term's position.
In our exercise, the sequence is specified by \(a_n = \frac{1}{n^2}\):
In our exercise, the sequence is specified by \(a_n = \frac{1}{n^2}\):
- The first term, \(a_1\), is \(1\).
- The second term, \(a_2\), is \(\frac{1}{4}\).
- The third term, \(a_3\), is \(\frac{1}{9}\).
- The hundredth term, \(a_{100}\), is \(\frac{1}{10000}\).