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Re: Inverse function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg99359] Re: [mg99301] Inverse function
  • From: "David Park" <djmpark at comcast.net>
  • Date: Sun, 3 May 2009 05:25:18 -0400 (EDT)
  • References: <13810515.1241259171501.JavaMail.root@n11>

You probably have to work a little more on using Mathematica for elementary
algebra - writing expressions and solving equations. In this case I think
the Inverse command has thrown you off.

For the reciprocal write:

1/(5/(2 - x))
(2 - x)/5

To get the actual inverse function you actually have to Solve for it.

Solve[y == 5/(2 - x), x][[1, 1]]
x -> (-5 + 2 y)/y


David Park
djmpark at comcast.net
http://home.comcast.net/~djmpark/  


From: davef [mailto:davidfrick2003 at yahoo.com] 


I have two questions: 

1. Is it possible to find the inveses function for one-to-one function in
Mathematica 7? 

For example the inverse of 5/(2-x) is 2-(5/x). I have tried Inverse and
InverseFunction but I cannot produce the inverse function. 

Can anyone explain how to get Mathematica to produce this result? (See
attached output screenshot.) 


2. Is it possible to change the format of the output for a recprical? 

For example, instead of writing the output of Inverse[5/(2-x)] as
(5/(2-x))^-1, can the output be set to produce (2-x)/5?




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