How can inverse functions help us find the range algebraically?

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The discussion centers on using inverse functions to find the range of the function \( f(x) = 125 - 12x \). The inverse function is determined as \( f^{-1}(x) = \frac{125 - x}{12} \), establishing that the domain of the inverse function is all real numbers, which indicates that the range of the original function is also all real numbers. The conversation highlights the necessity of restricting the domain of certain functions to ensure they are one-to-one, which is essential for finding their inverses. Additionally, it emphasizes the importance of graphical analysis and calculus for more complex functions.

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mathdad
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Find the range algebraically.

y = 125 - 12x

There is a way to do this by finding the inverse function. Can someone show me how to apply the idea of inverse functions to find the range?
 
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$f(x)=125-12x$, a 1-1 function

inverse is $f^{-1}(x) = \dfrac{125-x}{12}$

the domain of $f^{-1}(x)$ is $\mathbb{R} \implies$ range of $f(x)$ is $\mathbb{R}$
 
This function is one-to-one. Can we find the inverse of functions that are not one-to-one?

You found the inverse of the given function.

You then said that the domain of the inverse is the range of the original function.

Correct?

Can this method be applied to all functions?
 
Finding the inverse of a function is not always easy.

Sometimes the domain of the function in question must be restricted to force a 1-1 situation.

This is the reason why graphical analysis is so important. More complex graphs require the concepts of calculus to analyze.
 
You said:

"Sometimes the domain of the function in question must be restricted to force a 1-1 situation."

I am not too clear in terms of restricting a function "to force a 1-1 situation."

What do you mean by this statement which is so common in textbooks?
 

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