Finding the Inverse of f(x) = (2x-5)/(7x+4)

[luznyr]

Homework Statement

Find inverse of f(x) when f(x) = (2x-5)/(7x+4)

Homework Equations

none

The Attempt at a Solution

x=(2y-5)/(7y+4) and then i get stuck trying to rearrange back to y=...

 

[Dick]

Where do you get stuck?? Multiply both sides by 7y+4, move all of the terms with a y in them to one side and solve for y. It's not that hard.

 

[luznyr]

ok that gives x(7y+4) -2y= -5, 7xy+4x-2y=-5, so how do i get it back to y= then genius?

 

[danago]

Keep all your terms with 'y' in them on one side, and all the other terms on the other, and then take out a factor of 'y', and it should be clear from there.

 

[Dick]

So 4x+5=2y-7xy=y(2-7x). Can you solve for y now, genius?

 

[luznyr]

haha yep ty

 

[Dick]

BTW sorry about the 'it's not that hard' crack. If you don't see it, you don't see it.

 

[luznyr]

yeah sry bout the genius thing, thanks for the help anyone, much appreciated