Chapter 2: Problem 30
Estimating limits graphically and numerically Use a graph f \(f\) to estimate \(\lim f(x)\) or to show that the limit does not exist. Evaluate \(f(x)\) near \(x=a\) to support your conjecture. $$f(x)=\frac{3 \sin x-2 \cos x+2}{x} ; a=0$$
Short Answer
Expert verified
Answer: The limit does not exist.
Step by step solution
01
Mapping the function
First, let's rewrite the given function, f(x), for better understanding.
$$f(x) = \frac{3 \sin x - 2 \cos x + 2}{x}$$
Step 2: Evaluating the function values at different points near a
02
Function values near a
We need to evaluate the function values for x close to 0 (both negative and positive) to see if the function approaches a unique value or not.
Let's calculate \(f(x)\) for x = -0.1, -0.01, 0.01, and 0.1.
For x = -0.1, \(f(-0.1) \approx \frac{3 \sin(-0.1) - 2 \cos(-0.1) + 2}{-0.1} \approx -7.133\)
For x = -0.01, \(f(-0.01) \approx \frac{3 \sin(-0.01) - 2 \cos(-0.01) + 2}{-0.01} \approx -499.983\)
For x = 0.01, \(f(0.01) \approx \frac{3 \sin(0.01) - 2 \cos(0.01) + 2}{0.01} \approx 500.017\)
For x = 0.1, \(f(0.1) \approx \frac{3 \sin(0.1) - 2 \cos(0.1) + 2}{0.1} \approx 7.147\)
Step 3: Graphing the function
03
Graph analysis
Now, let's analyze the graph of the given function. After plotting the graph, we will find that there is a vertical asymptote at x = 0, which implies that the function does not approach any specific value as x approaches 0.
Step 4: Drawing a conclusion
04
Conclusion
Based on our numerical calculations and the graph analysis, we find that the function does not approach a unique value as x approaches 0. As a result, we can conclude that the limit does not exist:
$$\lim_{x\to0} f(x) = \lim_{x\to0} \frac{3 \sin x - 2 \cos x + 2}{x} = \text{Does not exist}$$
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graphical Limit Estimation
Graphical limit estimation involves analyzing the behavior of a function's graph as it approaches a specific value of x. By observing how the graph behaves near this point, we can guess whether a function converges to a particular number, diverges, or oscillates. In the context of the problem, plotting the graph of the function \( f(x) = \frac{3 \sin x - 2 \cos x + 2}{x} \) near \( x = 0 \) is crucial.
- Graph the function to visualize its behavior.
- Check for any breaks, sharp turns, or infinities at \( x = 0 \).
- Observe the function's behavior from both sides of the point \( x = 0 \).
Numerical Limit Calculation
Numerical limit calculation involves evaluating the function values close to the point of interest, in this case \( a = 0 \), to see if these values approach a common number.
We calculate \( f(x) \) at values like \( x = -0.1, -0.01, 0.01, \) and \( 0.1 \). These calculations help us observe the behavior of the function numerically.
We calculate \( f(x) \) at values like \( x = -0.1, -0.01, 0.01, \) and \( 0.1 \). These calculations help us observe the behavior of the function numerically.
- \( f(-0.1) \approx -7.133 \)
- \( f(-0.01) \approx -499.983 \)
- \( f(0.01) \approx 500.017 \)
- \( f(0.1) \approx 7.147 \)
Functions with Asymptotes
Functions that have asymptotes often show limits that do not exist, especially vertical asymptotes. An asymptote is a line that the graph of a function approaches but never actually touches. In the given function, there is a vertical asymptote at \( x = 0 \). This is evident by observing both the graph and the numerical values.
Understanding asymptotes is crucial:
Understanding asymptotes is crucial:
- Vertical asymptotes suggest that the function's values shoot off to infinity or negative infinity.
- They represent a limitation in the function's domain where a limit cannot exist due to unbounded behavior.
Limit Existence
The existence of a limit depends on the function approaching a single, finite value as \( x \) approaches a specific point. In our exercise, the aim is to determine the behavior of the function \( f(x) = \frac{3 \sin x - 2 \cos x + 2}{x} \) as \( x \to 0 \). For a limit to exist, the left-hand limit \( \lim_{x \to 0^-} \) and the right-hand limit \( \lim_{x \to 0^+} \) must converge to the same value.
Steps to determine limit existence:
Steps to determine limit existence:
- Evaluate the behavior of \( f(x) \) from both negative and positive sides of \( a \).
- Check if the function values stabilize to a single number.