Question
If $V=x y /\left(x^{2}+y^{2}\right)^{2}$ and $x=r \cos \theta, y=r \sin \theta$, show that $\frac{\partial^{2} V}{\partial r^{2}}+\frac{1}{r} \frac{\partial V}{\partial r}+\frac{1}{r^{2}} \frac{\partial^{2} V}{\partial 0^{2}}=0$
Step 1
We know that $x = r\cos\theta$ and $y = r\sin\theta$. Substituting these into $V$, we get: \[V = r\cos\theta \cdot r\sin\theta / (r\cos\theta)^{2}+(r\sin\theta)^{2})^{2} = r^{2}\cos\theta\sin\theta / r^{4} = \frac{\sin\theta\cos\theta}{r^{2}}.\] Show more…
Show all steps
Your feedback will help us improve your experience
Carson Merrill and 63 other educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
$\begin{aligned} \text { If } z=f(x, y), \text { where } x &=r \cos \theta \text { and } y=r \sin \theta, \text { show that } \\ \frac{\partial^{2} z}{\partial x^{2}}+\frac{\partial^{2} z}{\partial y^{2}} &=\frac{\partial^{2} z}{\partial r^{2}}+\frac{1}{r^{2}} \frac{\partial^{2} z}{\partial \theta^{2}}+\frac{1}{r} \frac{\partial z}{\partial r} \end{aligned}$
Partial Derivatives
The Chain Rule
If z=e^x siny, where x=st^2 and y=s^2 t, find ∂z/∂s and ∂z/∂t.
Transcript
18,000,000+
Students on Numerade
Trusted by students at 8,000+ universities
Watch the video solution with this free unlock.
EMAIL
PASSWORD