Given
2x+3
f(x) = ---------
x-2
1) replace "f(x)" with "y:"
2x+3
y = ---------
x-2
2) Interchange x and y:
2y+3
x = ---------
y-2
3) Solve this new equation for y:
xy -2x = 2y+3, so xy - 2y = 3 + 2x, or y(x-2) = 3 + 2x, or
3+2x
y = -----------
x-2
4) Replace y with
-1
f (x) and copy down the right side of the above equation.