Transformations, Algebra Trouble

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Homework Help Overview

The discussion revolves around finding the inverse of the function f(x) = (2x + 1) / (x + 2). The original poster expresses difficulty in manipulating the equation to isolate y and determine the inverse function.

Discussion Character

  • Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to rearrange the equation by switching x and y and expresses confusion about the steps involved in isolating y. Some participants question the methods used and suggest factoring as a potential approach to simplify the expression.

Discussion Status

Some participants indicate that the original poster's final answer is correct, while others provide guidance on factoring and manipulating the equation further. There appears to be a productive exchange of ideas regarding the steps to isolate y.

Contextual Notes

The original poster mentions feeling uncertain about their understanding of the topic, indicating a potential gap in their knowledge or experience with similar problems.

Linday12
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Homework Statement

If f(x)=[tex]\frac{2x+1}{x+2}[/tex], the equation for y=f^-1(x) is?
So I switch x, x=[tex]\frac{2y+1}{y+2}[/tex]

The Attempt at a Solution


I've tried many ways, but I must be going wrong somewhere, here's what I think to be my nearest:
x(y+2)=2y+1
x(y)+2x=2y+1
x(y)+2x-2x=2y+1-2x
x(y)=2y+1-2x
x(y)-2y=1-2x
And that's as far as I get, it seems I'm stuck in an endless x loop or it simplifies too much to get the correct answer, so I must be missing a vital step or rule.
Sorry, it has been a while since I've done this, and I'm not quite sure if I am even attempting it right. Any tip would be very helpful, I think the answer is:
y=[tex]\frac{1-2x}{x-2}[/tex]

Thank you.
 
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The answer is correct.

x(y)-2y=1-2x
y(x-2)=1-2x
 
Interesting. Let me see if I understand.

x(y)-2y=1-2x <----Am I to factor(not sure if that's the proper word) the left side to get that final answer then, similar to what you showed?

And then I get y(x-2) after the factor
Which then is y(x-2)=1-2x
And then I can get my final answer of:
y=[tex]\frac{1-2x}{x-2}[/tex]

So that is all I was missing? Then it makes sense now. Thank you very much!
 
Yep just factor and then divide by x-2 on both sides.
 

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