$\begin{array}{1 1} (a)\; 3x^3-4x^2+2x-12 \\(b)\; 3x^3+12x^2-2x-12 \\ (c)\;3x^3-12x^2+2x-12 \\(d)\; 3x^2-12x^2-2x-12 \end{array}$