Recent content by jschmid2

  1. J

    How to Find Extrema of Linear Functions on a Sphere?

    That is exactly what I needed. Thank you so much for the hint! :)
  2. J

    How to Find Extrema of Linear Functions on a Sphere?

    So, I seem to be drawing some blanks - my calc III is a little rusty. Find the max(2x+2y+z) and min(2x+y+z) on the surface x2+y2+z2=1 At first I thought I would take partial derivatives, but none of them yield 0, so that's not going to work. Any suggestions would be mighty helpful because...
  3. J

    Proving $\left\|(A-\lambda I)^{-1}\right\|_{2}$ with Inverse of A

    Could someone please help me show that if A is Hermitian \left\|(A-\lambda I)^{-1}\right\|_{2}=\frac{1}{min_{\lambda_{i}\in\sigma(A)}|\lambda-\lambda_{i}|} where \sigma(A) denotes the eigenvalues of A. I have figured out how to solve the norm without an inverse, but the inverse confuses me...
  4. J

    Linear ODE Non-constant coefficient

    Thanks so much. It reminded me of Cauchy-Euler, but I did not know how to approach it with lambda=0.
  5. J

    Linear ODE Non-constant coefficient

    Hi. I'm having difficulty remembering how to solve for u(r). The equation is r*u''+u'=0 with BC u(2)=20; u(1)=540. Any help would be appreciated. I really need help setting up how to solve. Thanks.
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