Evaluating Multivariable Limit: (x^2+y^2)/(1+y^2)

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Homework Help Overview

The discussion revolves around evaluating the multivariable limit of the expression (x^2+y^2)/(1+y^2) as (x,y) approaches (0,0). Participants are exploring whether the limit exists and the implications of their findings.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • The original poster expresses uncertainty about the limit's existence, noting differing values when approaching along the x and y axes. Other participants question the validity of simple substitution and discuss the continuity of the functions involved.

Discussion Status

The discussion is active, with participants presenting differing viewpoints on the limit's existence. Some suggest that the limit does exist based on continuity arguments, while others remain skeptical and seek further clarification.

Contextual Notes

Participants are grappling with the implications of continuity and the behavior of the function near the point of interest. There is an acknowledgment of potential confusion regarding the application of limits in multivariable contexts.

marquitos
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Multivariable Limits!

Lim (x^2+y^2)/(1+y^2)
(x,y)--> (0,0)

evaluate the limit or determine that it does not exist.
Im pretty sure that the limit does not exist because if i take it from the y and x axises the values don't match up but not really sure if that is the right way to do it. Any help would be great thank you very much.
 
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i apologize i think may be a very stupid question since simple substitution should most likely work but if it doesn't please inform me what i am doing wrong! Thank you again.
 


marquitos said:
i apologize i think may be a very stupid question since simple substitution should most likely work but if it doesn't please inform me what i am doing wrong! Thank you again.

The denominator approaches 1, doesn't it? I'm pretty sure the limit does exist.
 


Its a theorem that if f, g are continuous and g(x) != 0 then f/g is continuous at x. (1 + y^2) and (x^2 + y^2) are both continuous and (1+y^2) is never zero. Hence (x^2 + y^2)/(1+y^2) is continuous everywhere. So the limit is the value of the function at all points including zero.
 

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