Find the asymptotes of y = (x + 6)
                           -------
                           (x - 4)

   Verticle asymptotes: 
    equate denominator to 0:
    (x - 4) = 0, thus x = 4.  It is at x = 4 where the function is NOT defined.
    Lets see what values of x we get as y increases:
        y           x
      -------     ------
        0          -6
       10          5.11
       100         4.10
       1000        4.01
       10000       4.001

    It is obvious that as y increases, x approaches 4 but never reaches it.

    Lets see about when y decreases:
        y            x
      -------     -------
        0           -6
       -10          3.09
       -100         3.90
       -1000        3.990
       -10000       3.999

     As y decreases, x still approaches 4.  Therefore, a verticle asymptote
     appears at x = 4!

    Horizontal asymptotes:
    Divide both numerator and denominator by x (highest power of x):
    y = (1/x)(x + 6)      1 + (6/x)        1 + 0
        ------------  =  -----------  =  --------  =  1
        (1/x)(x - 4)      1 - (4/x)        1 - 0

    y = 1 is the horizontal asymptote!

    As x approaches positive infinity, y approaches 1, and when x approaches 
    negative infinity, y approaches 1.  See below:
         x          y
      -------    --------
         1       -2.333
        10        2.667
        100       1.104
       1000       1.010

    and     x            y
         --------     --------
            -1           -1
           -10          0.285
           -100         0.904
           -1000        0.990