Since you weren't very specific, I'm going to guess your question and help you with it.
No, [tex]x^3/(2x^2-3x)[/tex] is not a polynomial; it's a rational function. You can think of this as the ratio of two polynomials. It doesn't exist when the 'denominator' polynomial has a zero. Can you solve that one? Hint: quadratics have two solutions (usually, and this one does). Be careful when dividing!