Find Inverse of Function: Homework Help

  • Thread starter Thread starter GHealy
  • Start date Start date
  • Tags Tags
    Inverse
Click For Summary

Homework Help Overview

The original poster seeks assistance in finding the inverse of a function, specifically f(x) = (x + 2)/(3x + 5). They express uncertainty about handling the algebra involved, particularly with x in the denominator.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the process of switching variables and isolating y. Some suggest using properties of equality to derive a formula for y, while others question whether the result will be a valid function.

Discussion Status

Several participants have offered guidance on manipulating the equation to isolate x in terms of y. The discussion is ongoing, with different interpretations of the algebraic steps being explored.

Contextual Notes

The original poster mentions having forgotten some algebraic techniques and expresses a desire to refresh their understanding before an upcoming test. There is an acknowledgment of the challenge posed by the function's structure.

GHealy
Messages
3
Reaction score
0

Homework Statement


I need to pass a test to get into college calculus, but there's a few things I've forgotten since may, one of them being how to find the inverse of a function with x in the denominator. I think I remember it being something really simple that I'm overlooking, but here it goes:

Homework Equations


f(x) = (x + 2)/(3x + 5)

1) y = (x + 2)/(3x + 5)
2) x = (y + 2)/(3y + 5)
3) this is where it starts to go crazy.

The Attempt at a Solution


My attempts were kind of convulsive, but I hope it'll suffice to say that I know to switch y with x, then solve the problem for y, which will be the inverse. I just don't know how to get y out of the denominator without getting a really complicated answer. (edit: I put what I was saying into math form above)

Thanks, if anyone knows this. I've done some re-learning in the past week or so; there are just a few things left that are too specific to find online.
 
Physics news on Phys.org
Your goal is to use properties of equality of real numbers to find a formula for y. Either you can find a result or you cannot. Can you obtain an inverse in that general manner?
In fact, a result is possible; whether the result is a function, I leave for you to decide.
 
If the y=\frac{x + 2}{3x + 5} then x+2=y(3x+5). Your goal is to present x in terms of y. Now can you proceed?
 
Дьявол said:
If the y=\frac{x + 2}{3x + 5} then x+2=y(3x+5). Your goal is to present x in terms of y. Now can you proceed?

That's where I get, but I can't go further without jumbling the whole thing up.
 
GHealy said:
That's where I get, but I can't go further without jumbling the whole thing up.

Distribute the y on the right hand side, separate y and non-y terms to opposite sides, factor out y and divide.

--Elucidus
 
Elucidus said:
Distribute the y on the right hand side, separate y and non-y terms to opposite sides, factor out y and divide.

--Elucidus

*facepalm*

I can't believe I forgot simple algebra. Thanks.
 
What I did was, multiply the numerator and then expand everything. Bring all the x-terms and the xy-terms to one side, and the y-terms and constants to the other. Then I factored out x, and divided by the other stuff!
Good luck =)
 
Last edited:

Similar threads

  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 19 ·
Replies
19
Views
3K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
7
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K