Chapter 2: Problem 33
\(31-36\) Each limit represents the derivative of some function \(f\) at some number a. State such an \(f\) and a in each case. $$\lim _{x \rightarrow 5} \frac{2^{x}-32}{x-5}$$
Short Answer
Expert verified
The function is \(f(x) = 2^x\) and the point \(a = 5\).
Step by step solution
01
Identify the Derivative Form
We start by recognizing the format of the limit. The expression \(\lim _{x \rightarrow a} \frac{f(x) - f(a)}{x-a}\) is the definition of the derivative of a function \(f(x)\) at \(x = a\).
02
Determine Function and Point a
Given the expression \(\lim _{x \rightarrow 5} \frac{2^{x} - 32}{x - 5}\), we compare it to the derivative definition. Here, \(f(x) = 2^x\) and the point \(a\) is 5 because \(2^5 = 32\).
03
Verify the Expression
Substitute \(f(a) = 2^5 = 32\) back into the limit expression to confirm: \(\lim _{x \rightarrow 5} \frac{2^{x} - 32}{x-5}\). This matches the derivative form at \(x = a = 5\).
04
State the Function and the Point
The function \(f(x)\) is \(2^x\) and the point \(a\) where the derivative is being taken is 5.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Limit Definition of Derivative
The limit definition of the derivative is a fundamental concept in calculus. It defines the derivative as the limit of the difference quotient as the variable approaches a specific value. This means the derivative is the slope of the tangent line to the curve of a function at a specific point. The formula used is: \[ \lim_{x \to a} \frac{f(x) - f(a)}{x-a} \] In this expression:
- \( f(x) \) represents the function
- \( f(a) \) is the function value at a specific point \( a \)
- \( x \) approaches \( a \)
Exponential Functions
Exponential functions are powerful mathematical expressions, represented by \( f(x) = a^x \), where \( a \) is a constant and \( x \) is the exponent. These functions are known for their rapid growth or decay, based on the value of the base \( a \). For example, when \( a > 1 \), the function grows exponentially. In the exercise, the function involved was \( 2^x \), an exponential function. It’s essential to understand that:
- Exponential functions have a constant base raised to the power of a variable.
- They appear frequently in contexts of growth, such as populations or investments.
- These functions are smooth and continuous, making them suitable for derivative calculations using limits.
Calculus
Calculus is a vast field of mathematics focused on change and motion. It primarily consists of two main branches: differential calculus and integral calculus. The derivative, a key calculus concept, measures how a function value changes as its input changes.
In our context, differential calculus helps us find the derivative of a function, essential for understanding rates of change. Using the limit definition of the derivative, we can determine the slope of a tangent line to any function's curve, revealing important insights about the function's behavior.
Key aspects of branch calculus include:
- Understanding how functions change over time or various conditions.
- The ability to compute derivatives, which are crucial for optimization problems.
- Developing a deep comprehension of mathematical models in physical sciences and engineering.
Function Notation
Function notation is a way to represent functions in a clear and concise manner. A function is often written as \( f(x) \), where \( f \) names the function and \( x \) represents the input variable. This notation is crucial for expressing mathematical ideas effectively. For instance, in the given exercise, \( f(x) = 2^x \) denotes an exponential function. The notation easily allows:
- Clear identification of the function's formula, i.e., how to compute \( f(x) \) for each \( x \).
- Simplification in expressing operations, such as differentiation or integration.
- An organized framework for expressing complex mathematical relationships and their manipulations.