Domain of z= ln ( (x^2) + (y^2) )

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SUMMARY

The domain of the function z = ln((x^2) + (y^2)) is defined as x ≠ 0 and y ≠ 0, which indicates that both x and y cannot simultaneously equal zero. However, participants in the discussion argue that the notation may be misleading, suggesting that the intended meaning could be "x ≠ 0 or y ≠ 0." This interpretation allows for either variable to be zero while the other is not, expanding the domain. The confusion arises from the use of a comma, which is typically interpreted as "and" in mathematical contexts.

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Homework Statement


the given ans is x ≠ 0 , y ≠ 0 , the ans given is x ≠ 0 , y ≠ 0 . I don't understand the ans , why the author leave the ans like this ?

IMO , x can be 0 as long as y not = 0
y also can be 0 , as long as x not = 0 ,by giving the ans in x ≠ 0 , y ≠ 0 , the author just rule out the possibility above ?

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The Attempt at a Solution

 
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I guess "x ≠ 0 , y ≠ 0" was meant as "x ≠ 0 or y ≠ 0". The comma is misleading here.
 
mfb said:
I guess "x ≠ 0 , y ≠ 0" was meant as "x ≠ 0 or y ≠ 0". The comma is misleading here.
I agree. A comma is typically used as shorthand for "and".
 

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