Finding the inverse of a function.

[sxandr6]

f(x)=x + 4

.......x - 3

 

I know I need to change f(x) to y and then switch x and y. I got that far I tried to multiply both sides by (y-3) in order to solve for y, but after that I got a little lost.

[DJBruce]

[math]\frac{}{}[/math]So you have:

 

[math]x=\frac{y+4}{y-3}[/math]

[math]x(y-3)=(y+4)=xy-3x[/math]

 

Try to isolate all the y's on one side of the equation (Hint distribute the x). Once you have only terms containing y on one side factor something out. Then simply move the x over by dividing.

[sxandr6]

But wouldn't that elminate the y's.

 

y-y= 3x+4/x

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Merged post follows:

Consecutive posts merged

oh wait nevermind I got it, thanks for your help.

[thenewb]

y+4 = xy - 3x

y-xy = -4-3x

y(1-x)= -4-3x

y=(-4-3x)/(1-x)

[DJBruce]

Remember the rules thenewb people are not suppose to completely do the problem for others. You can help guide people, but are not suppose to do it for them.

Edited November 19, 2009 by DJBruce
Added link.