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Homework Help: Limit of multi variable func.

  1. Oct 28, 2011 #1
    1. The problem statement, all variables and given/known data

    (x,y)-->(0,0) y*ln (y2+x2)

    2. Relevant equations


    3. The attempt at a solution
    i've tried polar coordinates i end up with sinθ in it don't know how to proceed

    and i've taken several paths like y=0 , x=0 , x=y2 , x=y , x=y3
    they all yeild zero

    Edit : is it right if i after making polar sub. to say that :

    r*sinθ * ln r2 [itex]\leq[/itex] r*ln r2
    because if its right then problem solved :P
    Last edited: Oct 28, 2011
  2. jcsd
  3. Oct 28, 2011 #2


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    Science Advisor
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    Almost. You need absolute values:

    |r*sinθ * ln r2| [itex]\leq[/itex] r*|ln (r2)|
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