Chapter 2: Problem 39
Write the first five terms of the sequence \(\left\\{a_{n}\right\\}\), \(n=0,1,2,3, \ldots\), and find \(\lim _{n \rightarrow \infty} a_{n}\). $$ a_{n}=\frac{n}{n+1} $$
Short Answer
Expert verified
The first five terms are 0, \(\frac{1}{2}\), \(\frac{2}{3}\), \(\frac{3}{4}\), and \(\frac{4}{5}\). The limit is 1.
Step by step solution
01
Calculate First Term
Substitute \(n = 0\) into the sequence formula to find \(a_0\). \[ a_0 = \frac{0}{0+1} = \frac{0}{1} = 0 \] Thus, the first term is 0.
02
Calculate Second Term
Substitute \(n = 1\) into the sequence formula to find \(a_1\). \[ a_1 = \frac{1}{1+1} = \frac{1}{2} \]Thus, the second term is \(\frac{1}{2}\).
03
Calculate Third Term
Substitute \(n = 2\) into the sequence formula to find \(a_2\). \[ a_2 = \frac{2}{2+1} = \frac{2}{3} \]Thus, the third term is \(\frac{2}{3}\).
04
Calculate Fourth Term
Substitute \(n = 3\) into the sequence formula to find \(a_3\). \[ a_3 = \frac{3}{3+1} = \frac{3}{4} \]Thus, the fourth term is \(\frac{3}{4}\).
05
Calculate Fifth Term
Substitute \(n = 4\) into the sequence formula to find \(a_4\). \[ a_4 = \frac{4}{4+1} = \frac{4}{5} \]Thus, the fifth term is \(\frac{4}{5}\).
06
Derive the Limit
To find the limit of \(a_n\) as \(n\) approaches infinity, consider the expression:\[ a_n = \frac{n}{n+1} = \frac{n}{n} \cdot \frac{1}{1+\frac{1}{n}} \]As \(n\) becomes very large, \(\frac{1}{n}\) becomes negligible.Thus, \(a_n \approx \frac{1}{1} = 1\).So, the limit \(\lim_{n \to \infty} a_n = 1\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Calculus Sequences
Calculus provides a framework for understanding changes and behaviors within sequences and series. A sequence in calculus is a set of numbers ordered in a linear fashion such as \(a_0, a_1, a_2, \ldots \). Each number in the sequence is called a term. Sequences could be finite or infinite. In this context, we are dealing with a sequence defined by a formula, \(a_n = \frac{n}{n+1}\). This formula dictates how each term \(a_n\) is related to its position \(n\) within the sequence. To better understand sequences, we calculate specific terms:
- For \(n = 0\), \(a_0 = 0\)
- For \(n = 1\), \(a_1 = \frac{1}{2}\)
- For \(n = 2\), \(a_2 = \frac{2}{3}\)
- For \(n = 3\), \(a_3 = \frac{3}{4}\)
- For \(n = 4\), \(a_4 = \frac{4}{5}\)
Infinite Limits
Understanding infinite limits is integral in evaluating the behavior of sequences as their indices grow indefinitely. The limit of a sequence \(\lim_{n \to \infty} a_n\) essentially describes what value \(a_n\) approaches as \(n\) becomes very large. For the sequence \(a_n = \frac{n}{n+1}\), finding the limit involves simplifying the expression:
Notice that the major change as \(n\) increases is the effect of the \(\frac{1}{n+1}\) term becoming very small (or negligible). We approximate:
\[ a_n = \frac{n}{n+1} = \frac{n}{n} \cdot \frac{1}{1+\frac{1}{n}} \]
Since \(\frac{1}{n}\) approaches 0 as \(n\) approaches infinity, the expression simplifies:
\[ \frac{1}{1+\frac{1}{n}} \approx 1 \]
Thus \(a_n \approx 1\), leading us to conclude that the infinite limit of this sequence is 1: \(\lim_{n \to \infty} a_n = 1\). Understanding infinite limits help us grasp how sequences behave at the "ends" of their progressions.
Notice that the major change as \(n\) increases is the effect of the \(\frac{1}{n+1}\) term becoming very small (or negligible). We approximate:
\[ a_n = \frac{n}{n+1} = \frac{n}{n} \cdot \frac{1}{1+\frac{1}{n}} \]
Since \(\frac{1}{n}\) approaches 0 as \(n\) approaches infinity, the expression simplifies:
\[ \frac{1}{1+\frac{1}{n}} \approx 1 \]
Thus \(a_n \approx 1\), leading us to conclude that the infinite limit of this sequence is 1: \(\lim_{n \to \infty} a_n = 1\). Understanding infinite limits help us grasp how sequences behave at the "ends" of their progressions.
Convergence of Sequences
In calculus, a sequence is said to converge if it approaches a specific value as the index (\(n\)) goes to infinity. This destination value is known as the limit of the sequence. If the sequence \(a_n = \frac{n}{n+1}\) converges, it means that the terms settle towards a particular number. This behavior is crucial in understanding the long-term impact or stability of scenarios modeled by sequences.
Convergence can be visualized:
Convergence can be visualized:
- The terms: \(\frac{1}{2}, \frac{2}{3}, \frac{3}{4}, \frac{4}{5}, \ldots\) are getting closer to 1 as they progress.
- The closer the terms get to 1, the slower their rate of change becomes.
- Eventually, as \(n\) reaches very high values, \(a_n\) resides near 1.