Originally Posted by

**s3a** Normally when you try to find f-1(x) you just switch the x and the y

No, you don't. Instead of expressing y as a function of x you do the other way around: express x as a function of y. This is not "switching places" between x, y, otherwise you'd get for the inverse function EXACTLY the same expression as for the original function, which is not the case...and, btw, which is NOT what you did: you did the correct thing.

for example:

f(x) = x+3

x = y + 3

y = x - 3

f-1(x) = x- 3

but in the following problem:

"The formula C = 5/9(F-32), where F>= - 459.67, expresses the Celsius temperature C as a function of the Fahrenheit temperature F. Find a formula for the inverse function and interpret it. What is the domain of the inverse function?"

The answer for the formula is F = 9/5*C + 32 which I also obtain if I __solve for F__ (Note NOT switch the places of x (in this case F) and y (in this case C). My question is: **why is this the case?**

Could someone please explain the reasoning to me?

Thanks in advance!