Assume that the function f is a one-to-one function

If f(6)=4, find f^−1(4).

and

The same thing but when given the inverse:

If f^−1(−2)=−5, find f(−5).

- Jan 20th 2010, 12:36 PMLolcatsFinding the Inverse of a function when not given what f(x) is
Assume that the function f is a one-to-one function

If f(6)=4, find f^−1(4).

and

The same thing but when given the inverse:

If f^−1(−2)=−5, find f(−5). - Jan 20th 2010, 12:48 PMDrexel28
- Jan 20th 2010, 12:51 PMHallsofIvy
Use the

**definition**of "inverse function", of course! That is, if y= f(x) , then $\displaystyle x= f^{-1}(y)$. If $\displaystyle 4= f(6)$, that is, x= 6 and y= 4, $\displaystyle f^{-1}(y)= f^{-1}(y)= x= ?$.

Of course, if $\displaystyle x= f^{-1}(y)$ then y= f(x) so the other should be easy now. - Jan 20th 2010, 06:47 PMLolcats
Thank you! That makes alot of sense!