Tìm đa thức A để 1) \(\frac{3x^2y^2}{9xy^2} = \frac{A}{3y}\) 2) \(\frac{x-x^2}{5x^2-x} = \frac{x}{A}\) 3) \(\frac{A}{6x^2+3x} = \frac{2x-1}{4x^2-1}\) 4) \(\frac{A}{2x+1} = \frac{6x^2-3x}{4x^2-1}\) 5) \(\frac{5(y-x)^2}{5x^2-5xy} = \frac{x-y}{A}\) 6) \(\frac{x^2+8}{2x-1} = \frac{3x^3+24x}{A}\)