Chapter 2: Problem 43
Find the limits. $$\lim _{x \rightarrow 0}(2 \sin x-1)$$
Short Answer
Expert verified
The limit is -1.
Step by step solution
01
Understand the Expression
The function given is \( f(x) = 2 \sin x - 1 \). We need to find the limit of this function as \( x \) approaches 0.
02
Evaluate the Sine Function at 0
Recall that \( \sin x \) is a continuous function and \( \sin(0) = 0 \). This means we can substitute \( x = 0 \) directly into the sine function.
03
Calculate the Value of the Given Function at x = 0
Substitute \( \sin(0) = 0 \) back into the expression: \( 2\sin(0) - 1 = 2 \times 0 - 1 = -1 \).
04
Conclude the Limit
Since \( \sin x \) is continuous and we have evaluated it directly at \( x = 0 \), we conclude that the limit \( \lim_{x \to 0}(2 \sin x - 1) = -1 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Sine Function
The sine function, denoted as \( \sin x \), is one of the fundamental functions in trigonometry. It describes a smooth, repeating wave pattern, which is central to many mathematical and real-world applications, such as sound waves and alternating current.
- *Wave Nature*: The sine function maps angles to their sine values, giving outputs that range from -1 to 1.
- *Periodicity*: Sine waves repeat every \( 2\pi \), meaning \( \sin(x + 2\pi) = \sin x \).
- *Symmetry*: The function is odd, so \( \sin(-x) = -\sin x \).
Continuous Functions
Continuous functions are those that exhibit no sudden jumps or interruptions in their graphs. For a function to be continuous at a point, the following must hold:
This property was used in the step-by-step solution to plug \( x = 0 \) into \( \sin x \) and find the limit of the overall function easily.
- *The function is defined at that point.*
- *The limit of the function exists as it approaches the point.*
- *The function's value equals its limit at that point.*
This property was used in the step-by-step solution to plug \( x = 0 \) into \( \sin x \) and find the limit of the overall function easily.
Evaluating Limits
Evaluating limits is a foundational concept in calculus. It involves finding the value that a function approaches as the input approaches a certain point.
There are several ways to evaluate limits, such as:
There are several ways to evaluate limits, such as:
- **Direct Substitution**: Simply substitute the point into the function, which works well when dealing with continuous functions, like in this problem.
- **Factoring and Simplifying**: Useful for functions that initially appear to be undefined at the point.
- **L'Hopital's Rule**: Applies when direct substitution leads to indeterminate forms like \( \frac{0}{0} \).