Continuity of a two-variable function

In summary, the conversation discusses a problem involving b/ and d/ and the use of a norm function. The person is unsure if using the formula is a good idea. They also mention being able to prove a function is not continuous by finding different values for x and y. A hint is given for solving part (b) of the problem involving polar coordinates and approaching a limit.
  • #1
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Homework Statement



Capture.JPG


Homework Equations



My main problem is connected with b/ and d/. I found a formula involving the norm of the function, but I'm not sure if it's a good idea using it.

The Attempt at a Solution



I can prove that a function is not continuous by finding different values for x and y for which the limit at the point is approaching different values, but have no idea how to prove that it is continuous.
 
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  • #2
Hint for (b): Look at

[tex]\left| \frac{(2x+y)^3+x^2+y^2}{x^2+y^2} - 1\right| [/tex]

Simplify it and change it to polar coordinates. Think about [itex]r\rightarrow 0[/itex].
 
  • #3
Thank you
 

What is the definition of continuity for a two-variable function?

The continuity of a two-variable function means that the function is unbroken or connected at all points in its domain. This means that as the values of both variables change, the output of the function changes smoothly without any abrupt jumps or breaks.

How can I determine if a two-variable function is continuous at a specific point?

To determine if a two-variable function is continuous at a specific point, you can evaluate the function at that point and see if it approaches the same output value from both sides. If it does, then the function is continuous at that point. Additionally, you can also use the limit definition of continuity to prove continuity at a specific point.

Can a two-variable function be continuous at some points but not others?

Yes, a two-variable function can be continuous at some points and not others. This means that there may be certain points in the domain where the function is not connected or has a jump or break. However, it is still possible for the function to be continuous at other points in its domain.

What is the difference between continuity and differentiability for a two-variable function?

Continuity and differentiability are closely related but not the same. Continuity means that a function is unbroken and connected at all points in its domain, while differentiability means that a function has a well-defined derivative at a point. A function can be continuous but not differentiable, but if a function is differentiable at a point, it must also be continuous at that point.

How can I use the concept of continuity to solve problems involving two-variable functions?

The concept of continuity can be used to solve problems involving two-variable functions by helping us understand how the function behaves at different points in its domain. By analyzing the continuity of a function, we can determine whether it has any breaks or jumps, and use this information to make predictions about its behavior and solve problems involving the function.

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