What you have posted means the following:
. . . . .\(\displaystyle \L f(x)\, =\, -3x^2\, + \,2x\, - \,\frac{1}{x^2}\, +\, 2x\, - \, 15\)
Is that what you meant? Or did you mean this?
. . . . .\(\displaystyle \L f(x)\, =\, \frac{-3x^2\, + \, 2x\, - \, 1}{x^2\, +\, 2x\, - \, 15}\)
Or something else...?
Finding the vertical and horizontal asymptotes is fairly formulaic and was covered back in algebra. Where are you stuck?
Please be specific. Thank you.
Eliz.