Chapter 3: Problem 44
Compute the derivatives of the vector-valued functions. \(\mathbf{r}(t)=e^{t} \mathbf{i}+2 e^{t} \mathbf{j}+\mathbf{k}\)
Short Answer
Expert verified
\(\mathbf{r}'(t) = e^t \mathbf{i} + 2e^t \mathbf{j} \)
Step by step solution
01
Identify the Components of the Vector-valued Function
The given vector-valued function is \( \mathbf{r}(t) = e^{t} \mathbf{i} + 2e^{t} \mathbf{j} + \mathbf{k} \). This can be broken down into its component functions: \( x(t) = e^t \), \( y(t) = 2e^t \), and \( z(t) = 1 \).
02
Compute the Derivative of the First Component Function
Compute the derivative of the first component function \( x(t) = e^t \). Using the derivative rule for exponential functions, the derivative is \( \frac{dx}{dt} = e^t \).
03
Compute the Derivative of the Second Component Function
Compute the derivative of the second component function \( y(t) = 2e^t \). Since this function is a constant multiple of an exponential function, its derivative is \( \frac{dy}{dt} = 2e^t \).
04
Compute the Derivative of the Third Component Function
The third component function \( z(t) = 1 \) is a constant. The derivative of a constant function is \( \frac{dz}{dt} = 0 \).
05
Combine the Derivatives into the Derivative of the Vector-valued Function
Combine the computed derivatives into the vector form. Thus, the derivative of \( \mathbf{r}(t) \) is \( \mathbf{r}'(t) = e^t \mathbf{i} + 2e^t \mathbf{j} + 0 \mathbf{k} \) or simply \( \mathbf{r}'(t) = e^t \mathbf{i} + 2e^t \mathbf{j} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Differentiation
Differentiation is a fundamental concept in calculus used to determine how a function changes as its input changes. For vector-valued functions, differentiation involves finding the rate of change of each component separately. This allows us to understand the behavior of the vector function as a whole.
To differentiate a vector-valued function like \( \mathbf{r}(t) = e^{t} \mathbf{i} + 2 e^{t} \mathbf{j} + \mathbf{k} \), follow these steps:
To differentiate a vector-valued function like \( \mathbf{r}(t) = e^{t} \mathbf{i} + 2 e^{t} \mathbf{j} + \mathbf{k} \), follow these steps:
- Break the function into its component functions: \( x(t) = e^t \), \( y(t) = 2e^t \), and \( z(t) = 1 \).
- Compute the derivative of each component: \( \frac{dx}{dt} = e^t \), \( \frac{dy}{dt} = 2e^t \), and \( \frac{dz}{dt} = 0 \).
- Combine these derivatives to form the derivative of the entire vector-valued function: \( \mathbf{r}'(t) = e^t \mathbf{i} + 2e^t \mathbf{j} \).
Exponential Functions
Exponential functions are a key part of both pure and applied mathematics. They are characterized by a constant base raised to a variable exponent. In our example, \( e^t \) is the exponential function in each component of \( \mathbf{r}(t) = e^{t} \mathbf{i} + 2 e^{t} \mathbf{j} + \mathbf{k} \).
Exponential functions have a unique property: their derivatives are proportional to the functions themselves.
This means:
Exponential functions have a unique property: their derivatives are proportional to the functions themselves.
This means:
- The derivative of \( e^t \) is \( e^t \).
- The derivative of \( 2e^t \) remains \( 2e^t \), because of the constant multiple rule.
Vector Calculus
Vector calculus extends calculus to vector-valued functions, encompassing operations like differentiation and integration to solve real-world problems involving curves, surfaces, and fields. Here, the focus is on differentiating vector-valued functions like \( \mathbf{r}(t) = e^{t} \mathbf{i} + 2 e^{t} \mathbf{j} + \mathbf{k} \).
Vector calculus provides tools to:
Vector calculus provides tools to:
- Find the rate of change in any direction by calculating derivatives of vector functions.
- Understand vector fields, such as those in electromagnetism and fluid dynamics.