Elliott Crawford
12/16/2023 · Primary School
Considering \( x \) and \( y \) as independent variables, find \( \frac{\partial r}{\partial x}, \frac{\partial r}{\partial y}, \frac{\partial \theta}{\partial x}, \frac{\partial \theta}{\partial y} \) when \( x=e^{2 r} \cos \theta \) \( y=e^{3 r} \sin \theta \)
UpStudy ThothAI Solution
Tutor-Verified Answer
Step-by-step Solution
To find the partial derivatives \( \frac{\partial r}{\partial x} \), \( \frac{\partial r}{\partial y} \), \( \frac{\partial \theta}{\partial x} \), and \( \frac{\partial \theta}{\partial y} \) given the equations \( x = e^{2r} \cos \theta \) and \( y = e^{3r} \sin \theta \), we will use implicit differentiation and the chain rule.
### Step 1: Express \( r \) and \( \theta \) in terms of \( x \) and \( y \)
We have the following equations:
\[
x = e^{2r} \cos \theta
\]
\[
y = e^{3r} \sin \theta
\]
### Step 2: Differentiate with respect to \( x \) and \( y \)
#### Finding \( \frac{\partial r}{\partial x} \) and \( \frac{\partial \theta}{\partial x} \)
1. Differentiate \( x \) with respect to \( r \) and \( \theta \):
\[
\frac{\partial x}{\partial r} = 2 e^{2r} \cos \theta
\]
\[
\frac{\partial x}{\partial \theta} = -e^{2r} \sin \theta
\]
2. Differentiate \( y \) with respect to \( r \) and \( \theta \):
\[
\frac{\partial y}{\partial r} = 3 e^{3r} \sin \theta
\]
\[
\frac{\partial y}{\partial \theta} = e^{3r} \cos \theta
\]
#### Using the chain rule
Using the chain rule, we can express the derivatives of \( r \) and \( \theta \) in terms of \( x \) and \( y \):
\[
\begin{pmatrix}
\frac{\partial x}{\partial r} & \frac{\partial x}{\partial \theta} \\
\frac{\partial y}{\partial r} & \frac{\partial y}{\partial \theta}
\end{pmatrix}
\begin{pmatrix}
\frac{\partial r}{\partial x} \\
\frac{\partial \theta}{\partial x}
\end{pmatrix}
=
\begin{pmatrix}
1 \\
0
\end{pmatrix}
\]
This gives us the system of equations:
\[
\begin{pmatrix}
2 e^{2r} \cos \theta & -e^{2r} \sin \theta \\
3 e^{3r} \sin \theta & e^{3r} \cos \theta
\end{pmatrix}
\begin{pmatrix}
\frac{\partial r}{\partial x} \\
\frac{\partial \theta}{\partial x}
\end{pmatrix}
=
\begin{pmatrix}
1 \\
0
\end{pmatrix}
\]
#### Finding the inverse
To solve for \( \frac{\partial r}{\partial x} \) and \( \frac{\partial \theta}{\partial x} \), we need the inverse of the Jacobian matrix:
\[
J = \begin{pmatrix}
2 e^{2r} \cos \theta & -e^{2r} \sin \theta \\
3 e^{3r} \sin \theta & e^{3r} \cos \theta
\end{pmatrix}
\]
The determinant of \( J \) is:
\[
\text{det}(J) = (2 e^{2r} \cos \theta)(e^{3r} \cos \theta) - (-e^{2r} \sin \theta)(3 e^{3r} \sin \theta)
\]
\[
= 2 e^{5r} \cos^2 \theta + 3 e^{5r} \sin^2 \theta = e^{5r} (2 \cos^2 \theta + 3 \sin^2 \theta)
\]
The inverse of \( J \) is given by:
\[
J^{-1} = \frac{1}{\text{det}(J)} \begin{pmatrix}
e^{3r} \cos \theta & e^{2r} \sin \theta \\
-3 e^{3r} \sin \theta & 2 e^{2r} \cos \theta
\end{pmatrix}
\]
### Step 3: Solve for \( \frac{\partial r}{\partial x} \) and \( \frac{\partial \theta
Quick Answer
To find the partial derivatives \( \frac{\partial r}{\partial x} \), \( \frac{\partial r}{\partial y} \), \( \frac{\partial \theta}{\partial x} \), and \( \frac{\partial \theta}{\partial y} \), differentiate the given equations \( x = e^{2r} \cos \theta \) and \( y = e^{3r} \sin \theta \) implicitly with respect to \( x \) and \( y \), then use the chain rule and the inverse of the Jacobian matrix to solve for the derivatives.
Answered by UpStudy AI and reviewed by a Professional Tutor
UpStudy ThothAI
Self-Developed and Ever-Improving
Thoth AI product is constantly being upgraded and optimized.
Covers All Major Subjects
Capable of handling homework in math, chemistry, biology, physics, and more.
Instant and Accurate
Provides immediate and precise solutions and guidance.
Try Now
Ask Tutors
Ask AI
10x
Fastest way to Get Answers & Solutions
By text
Enter your question here…
By image
Re-Upload
Submit