How might I find the equation for one of the lines of symmetry for the hyperbola $$y= 2 + \frac 6{x-4},\,\text{ where x cannot equal}\; 4.$$
I know that the lines of symmetry for the rational function $y=A/x$ are $y=x$ and $y=-x$...and that to find the lines of symmetry of $y=A/(x-h) + k$, where x cannot equal $h$...the equations become $y-k=x-h$ and $y-k = -(x-h)$...but I don't know how to apply that for the problem above...any ideas?