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

  • Thread starter chetzread
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It could have been more clear if the author had used "or" instead of a comma.In summary, the given answer is x ≠ 0, y ≠ 0, but the author may have meant x ≠ 0 or y ≠ 0. The use of a comma instead of "or" may be misleading.
  • #1
chetzread
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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 ?

Homework Equations

The Attempt at a Solution

 
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  • #2
I guess "x ≠ 0 , y ≠ 0" was meant as "x ≠ 0 or y ≠ 0". The comma is misleading here.
 
  • #3
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".
 

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

1. What is the domain of z= ln((x^2) + (y^2))?

The domain of this function is all real numbers except for when both x and y are equal to zero. This is because the natural logarithm function is undefined when the input is zero, and in this case, both x^2 and y^2 would be equal to zero.

2. Can negative numbers be part of the domain of this function?

Yes, negative numbers can be part of the domain of this function. The natural logarithm function can accept negative numbers as input, as long as they are not zero. In this case, the function will return a complex number as the output.

3. Is the domain of this function the same for all values of x and y?

No, the domain of this function depends on the values of x and y. As mentioned before, the only restriction is that both x and y cannot be zero. Otherwise, the domain is all real numbers.

4. Can the domain of this function be extended to include complex numbers?

Yes, the domain of this function can be extended to include complex numbers. In this case, the function will return a complex number as the output. However, the natural logarithm function is not typically defined for complex numbers, so this extension may not be useful in most cases.

5. Are there any other restrictions on the domain of this function?

No, there are no other restrictions on the domain of this function. As long as both x and y are not zero, the function will be defined for all real numbers. However, it is important to note that the output of the function may still be limited or undefined for certain input values, such as negative numbers or extremely large numbers.

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