[tex]2x^3-2x^2-12x=2x(x^2-x-6)=(*)\\\\------------------------------\\x^2-x-6\\\\a=1;\ b=-1;\ c=-6\\\\\Delta=(-1)^2-4\cdot1\cdot(-6)=1+24=25\\\\\sqrt\Delta=\sqrt{25}=5\\\\x_1=\frac{1-5}{2\cdot1}=\frac{-4}{2}=-2;\ x_2=\frac{1+5}{2\cdot1}=\frac{6}{2}=3\\\\x^2-x-6=(x+2)(x-3)\\\\------------------------------\\\\(*)=2x(x+2)(x-3)[/tex]