[latex]W(x)=ax^3-x^2-12x+b\ r_1=-2\ r_2=frac{1}{3}\ left { {{W(r_1)=0} atop {W(r_2)=0}} ight. \ left { {{0=-8a-4+24+b} atop {0=frac{a}{27}-frac{1}{9}-4+b}} ight. \ \ left { {{8a-b=20} atop {a+27b=111}} ight. \ left { {{8a-b=20} atop {-8a-216b=-888}} ight.\ -217b=-868\ b=4\ a=3[/latex]
[latex] left { {{(-2)^3a-(2)^2-12*(-2)+b=0} atop {( frac{1}{3})^3a-(frac{1}{3})^2-12*( frac{1}{3})+b=0}} ight.\ left { {{-8a+b=-20} atop { frac{1}{27}a+b= frac{37}{9}}} ight.\ left { {{b=-20+8a} atop { frac{1}{27}a-20+8a= frac{37}{9}}} ight.\ left { {{b=-20+8a} atop { frac{217}{27}a-20= frac{37}{9}}} ight.\ left { {{b=-20+8a} atop { frac{217}{27}a= frac{217}{9}}} ight.\ left { {{b=-20+8a} atop { a=3}} ight.\ left { {{b=4} atop { a=3}} ight.\ [/latex]
