SOLUTION: If {{{y=f(x) = (3x + 7)/(4x - 9) }}}, show that {{{x = f(y)}}}

Sorry but that is just not true in general.  

Here is a disproof by a counterexample.

If it were true in general it would be true if x = 1

Suppose x = 1











Now in order for what we are asked to prove to be true in this
case, we must end up with

, which in this case would be



However f(-2) is found by substituting x=-2 in











which is false.  So what you were asked to
prove is not true.

Edwin