Finding The Limit Of A 3D Function

Baumer8993
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Homework Statement


Find the limit as X, and Y both approach 0 of (X2Y)/(X2 + Y4)


Homework Equations


The equation from above.


The Attempt at a Solution


I have been doing the technique of approaching from different lines such as y = x, or x = y,
x = 0, and y = 0. All of them give me a limit of zero, so that will not do. I graphed the function online, and it appears as if the function does have a limit of zero. How would I prove this? I think I need to do something with polar coordinates, but I am not sure how to do that.
 
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EDIT:
I'd go with SammyS's
 
Baumer8993 said:

Homework Statement


Find the limit as X, and Y both approach 0 of (X2Y)/(X2 + Y4)

Homework Equations


The equation from above.

The Attempt at a Solution


I have been doing the technique of approaching from different lines such as y = x, or x = y,
x = 0, and y = 0. All of them give me a limit of zero, so that will not do. I graphed the function online, and it appears as if the function does have a limit of zero. How would I prove this? I think I need to do something with polar coordinates, but I am not sure how to do that.
Yes. Change to polar coordinates.

x=r\cos(\theta)

y=r\sin(\theta)
 
Last edited:
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...

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