Continuity of the Inverse Function

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SUMMARY

The discussion centers on the theorem regarding the continuity of inverse functions in calculus. It states that if a function f(x) is continuous on an interval and one-to-one, then its inverse function is also continuous on its range. The example provided, with the functions y = -2/(x-5) and its inverse y = (5x-2)/x, illustrates the concept, although it is noted that neither function has a domain of all real numbers. The key takeaway is that continuity is preserved in inverse functions under the condition of one-to-one mapping.

PREREQUISITES
  • Understanding of basic calculus concepts, specifically functions and their inverses.
  • Familiarity with the definition of continuity in mathematical functions.
  • Knowledge of one-to-one functions and their significance in inverse functions.
  • Ability to manipulate and analyze rational functions.
NEXT STEPS
  • Study the properties of one-to-one functions and their implications for inverses.
  • Learn about the Intermediate Value Theorem and its relation to continuity.
  • Explore examples of continuous functions and their inverses in detail.
  • Practice problems involving the determination of domains and ranges of rational functions.
USEFUL FOR

Students beginning their studies in calculus, particularly those struggling with the concept of continuity and inverse functions. This discussion is also beneficial for educators seeking to clarify these concepts for their students.

bsmithysmith
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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:

$$y=\frac{-2}{x-5}$$
and the inverse
$$y=\frac{5x-2}{x}$$

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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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:

$$y=\frac{-2}{x-5}$$
and the inverse
$$y=\frac{5x-2}{x}$$

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.
 

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