# How do I find the inverse of a rational function?

• Jun 2nd 2009, 01:57 PM
s3a
How do I find the inverse of a rational function?
How do I find the inverse of the following rational function?:

y = -4(x-2)/(x+1)

Any help would be GREATLY appreciated!
• Jun 2nd 2009, 01:59 PM
Jhevon
Quote:

Originally Posted by s3a
How do I find the inverse of the following rational function?:

y = -4(x-2)/(x+1)

Any help would be GREATLY appreciated!

switch x and y

$x = \frac {-4(y - 2)}{y + 1}$

now solve for y, the resulting function is your inverse function
• Jun 2nd 2009, 02:24 PM
s3a
My problem is when it comes to solving for y.
• Jun 2nd 2009, 02:31 PM
yeongil
$x = \frac {-4(y - 2)}{y + 1}$

$x(y + 1) = -4(y - 2)$

$xy + x = -4y + 8$

$xy + 4y = -x + 8$

$y(x + 4) = -x + 8$

$y = \frac{-x + 8}{x + 4}$

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