I suspect that you are asked to find a function of the form and that you were just a bit lazy in leaving out the paranthesis around the denominator and numerator terms.

If so, the following system of equations can be used to determine a,b,c, and d:

This system has infinitenly many solutions, because it is possible to multiply numerator and denominator with the same constant to get another solution of the original problem. One, particularly nice solution (i.e. one with small, integral values for a,b,c, and d) is a=4, b=-1, c=3, d=2.