Chapter 10: Problem 29
Limits of sequences Find the limit of the following sequences or determine that the sequence diverges. $$\left\\{(0.5)^{n}+3(0.75)^{n}\right\\}$$
Short Answer
Expert verified
Answer: The limit of the sequence is 0.
Step by step solution
01
Identify the type of sequence and its terms
We are given the sequence:
$$a_n = (0.5)^n + 3(0.75)^n$$
It is an exponential sequence because both terms have a constant raised to the power of n.
02
Apply limit properties
We will apply the limit properties to the given sequence. Since it's a sum, we can take the limit of each term separately:
$$\lim_{n \to \infty} a_n = \lim_{n \to \infty} (0.5)^n + \lim_{n \to \infty} 3(0.75)^n$$
03
Determine the behavior of each term as n approaches infinity
Now, analyze each term individually.
1. For the term \((0.5)^n\): Since the base is less than 1, as n approaches infinity, the term will approach 0.
2. For the term \(3(0.75)^n\): Since the base (0.75) is also less than 1, as n approaches infinity, the term will approach 0.
04
Calculate the limit of the sequence
Now, calculate the limit of the given sequence:
$$\lim_{n \to \infty} a_n = \lim_{n \to \infty} (0.5)^n + \lim_{n \to \infty} 3(0.75)^n = 0 + 0 = 0$$
The limit of the given sequence is 0.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exponential Sequence
An exponential sequence is a series where each term is formed by raising a constant base to the power of the sequence index, called \( n \). This type of sequence can often be represented as \( a^n \), where \( a \) is the base and has a significant effect on the sequence's behavior as \( n \) grows. Some key characteristics are:
- The base \( a \) determines how the sequence grows or decays.
- If \( a > 1 \), the sequence grows exponentially.
- If \( 0 < a < 1 \), the sequence decays exponentially, heading towards zero.
Sequence Convergence
Sequence convergence is about whether a sequence eventually settles to a particular number, known as the limit. To determine convergence:
- Examine whether the sequence's terms get closer to a single value.
- If it does, the sequence converges.
- If not, the sequence is said to diverge.
Limit Properties
Limit properties refer to a set of rules and tactics that help us calculate the limit of more complex sequences. These properties make evaluating limits more manageable:
- The limit of a sum is the sum of the limits: \( \lim_{n \to \infty} (a_n + b_n) = \lim_{n \to \infty} a_n + \lim_{n \to \infty} b_n \).
- The limit of a product is the product of the limits if each limit exists.
- These properties allow breaking down sequences into simpler parts to find the limit.
Infinity Behavior
Infinity behavior involves understanding how a sequence acts as the index \( n \) tends toward infinity. Analyzing infinity behavior helps us predict long-term trends and the convergence of sequences.
- If a term's base is less than 1, as \( n \to \infty \), it tends to zero.
- If the base is exactly 1, the term stays constant.
- Bases greater than 1 indicate unbounded growth.