Continuity of the Inverse Function

In summary, the theorem states that if a function is continuous on an interval with a range, and its inverse exists, then the inverse function is also continuous on its domain. This means that if a function and its inverse both follow the same rules, they will also have the same properties of continuity. However, it is important to note that in order for this to apply, the original function must be one-to-one on its domain.
  • #1
bsmithysmith
23
0
I just started Calculus 1, a summer quarter that's compressed and I'm having trouble understanding a theorem that state continuity of the inverse function. Within my textbook, it mentions "If f(x) is continuous on an interval I with range R, and if inverse f(x) exists, then the inverse f(x) is continuos with domain R".

Not understanding it too much, but from what I can derive from it is that when a function has an inverse, it follows the same rules of the function; if that makes sense.

Lets say:

\(\displaystyle y=\frac{-2}{x-5}\)
and the inverse
\(\displaystyle y=\frac{5x-2}{x}\)

Then they both are continuous with their domains R. Maybe I'm not getting it, or can't put it in words, but it's a little confusing to me. They are the same equations, although inverses, but follow the same properties of continuity.

I need simplification because I also don't understand what I'm talking about, myself.
 
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  • #2
bsmithysmith said:
I just started Calculus 1, a summer quarter that's compressed and I'm having trouble understanding a theorem that state continuity of the inverse function. Within my textbook, it mentions "If f(x) is continuous on an interval I with range R, and if inverse f(x) exists, then the inverse f(x) is continuos with domain R".

Not understanding it too much, but from what I can derive from it is that when a function has an inverse, it follows the same rules of the function; if that makes sense.

Lets say:

\(\displaystyle y=\frac{-2}{x-5}\)
and the inverse
\(\displaystyle y=\frac{5x-2}{x}\)

Then they both are continuous with their domains R. Maybe I'm not getting it, or can't put it in words, but it's a little confusing to me. They are the same equations, although inverses, but follow the same properties of continuity.

I need simplification because I also don't understand what I'm talking about, myself.

Well first of all, it should be obvious that NEITHER of those functions has a domain of $\displaystyle \begin{align*} \mathbf{R} \end{align*}$.

Anyway, all that the theorem you're referring to is saying is that provided your original function is one-to-one on its domain (which is a requirement to have an inverse function), if your original function is continuous, so is the inverse function.
 

1. What is the definition of continuity of the inverse function?

Continuity of the inverse function refers to the property of a function where its inverse function is also continuous. This means that the inverse function has no abrupt changes or breaks in its graph and can be drawn without lifting the pen.

2. How is the continuity of the inverse function related to the continuity of the original function?

The continuity of the inverse function is directly related to the continuity of the original function. If the original function is continuous, then its inverse function will also be continuous. Similarly, if the original function is discontinuous, its inverse function will also be discontinuous.

3. Can a function have a continuous inverse if it is not one-to-one?

No, a function can only have a continuous inverse if it is one-to-one. This means that each element in the domain maps to a unique element in the range. If a function is not one-to-one, it will not have a well-defined inverse function.

4. How can we determine the continuity of the inverse function?

We can determine the continuity of the inverse function by checking the continuity of the original function and the one-to-one property. If the original function is continuous and one-to-one, then its inverse function will also be continuous. We can also use the intermediate value theorem to determine the continuity of the inverse function.

5. Are there any special cases where the inverse function is not continuous?

Yes, there are a few special cases where the inverse function may not be continuous. One example is when the original function has a vertical asymptote. In this case, the inverse function will have a horizontal asymptote, making it discontinuous. Another case is when the original function is piecewise continuous, the inverse function may have points of discontinuity at the breakpoints.

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