Chapter 4: Problem 22
In Exercises find \(d y / d x\). $$y=e^{1 / x}$$
Short Answer
Expert verified
\( \frac{dy}{dx} = -\frac{e^{1/x}}{x^2} \).
Step by step solution
01
Identify the Function and Inner Function
The given function is \( y = e^{1/x} \). Here, \( 1/x \) is the inner function. We see that \( y \) is an exponential function with the form \( e^u \), where \( u = 1/x \).
02
Differentiate the Outer Function
First, differentiate the outer function \( e^u \) with respect to \( u \). The derivative of \( e^u \) is \( e^u \).
03
Differentiate the Inner Function
Now, differentiate the inner function \( u = 1/x \) with respect to \( x \). The derivative of \( 1/x \) is \( -1/x^2 \).
04
Apply the Chain Rule
Apply the chain rule for differentiation, which states that if \( y = e^{u} \) and \( u = 1/x \), then \( \frac{dy}{dx} = \frac{dy}{du} \cdot \frac{du}{dx} \). Substituting the values, we have \( \frac{dy}{dx} = e^{1/x} \cdot \left(-\frac{1}{x^2}\right) \).
05
Simplify the Expression
Finally, simplify the expression to find \( \frac{dy}{dx} = -\frac{e^{1/x}}{x^2} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exponential Function
An exponential function is a type of mathematical function where a constant base is raised to a variable exponent. In the case of the given exercise, our exponential function is expressed as \( e^u \), where \( e \) is the natural exponential base and \( u \) is any real number or expression. The base \( e \) is an important constant approximately equal to 2.718, and it appears frequently in various areas of mathematics.
- Exponential functions grow at a rate proportional to their current value. This unique property makes them applicable in natural growth processes, such as population growth or radioactive decay.
- Derivatives of exponential functions maintain a similar form. For any function of the type \( e^u \), where \( u \) is a function of \( x \), the derivative with respect to \( u \) is still \( e^u \).
Chain Rule
The chain rule is a fundamental concept in calculus used for differentiating compositions of functions. When you have a function within another function — known as a composite function — the chain rule helps us find the derivative effectively. It essentially tells us how to differentiate a function of a function.
- The chain rule formula is stated as \( \frac{dy}{dx} = \frac{dy}{du} \cdot \frac{du}{dx} \), where \( y \) is the outer function and \( u \) is the inner function.
- This rule is particularly useful when dealing with complicated derivatives, to break them down into simpler parts.
- In the exercise provided, the chain rule allows us to differentiate the expression \( y = e^{1/x} \) by treating \( 1/x \) as \( u \), differentiating each part separately.
Inner Function
The inner function is the function that is embedded within another function in composite functions. In the provided exercise, the inner function is \( u = \frac{1}{x} \). Identifying the inner function is a crucial step in using the chain rule for differentiation.
- An inner function is differentiated with respect to its own variable, which in this case, results in the derivative \( \frac{du}{dx} = -\frac{1}{x^2} \).
- This step is aligned with the process of finding the derivative of a composite function by breaking down the functions into manageable parts.
Outer Function
The outer function in a composite function is the function that envelops the inner function. For the expression \( y = e^{1/x} \), the outer function is \( y = e^u \) after substituting \( u = 1/x \). Differentiating the outer function is usually the first step after identifying the inner function.
- The derivative of the exponential outer function \( e^u \) with respect to \( u \) is simply \( e^u \), demonstrating the self-similar property of exponential functions.
- After differentiating the outer function, this result is used in the chain rule to combine with the derivative of the inner function.