Solution - PolynomialRootFinder

$$factors\left(\left|a_0\right|\right)=1,2,3,6$$

$$factors\left(\left|a_n\right|\right)=1,2,3,4,6,7,12,14,21,28,42,84$$

$$x=+/-p/q=-1/84,1/84,-1/42,1/42,-1/28,1/28,-1/21,1/21,-1/14,1/14,-1/12,1/12,-2/21,2/21,-3/28,3/28,-1/7,1/7,-1/6,1/6,-3/14,3/14,-1/4,1/4,-2/7,2/7,-1/3,1/3,-3/7,3/7,-1/2,1/2,-2/3,2/3,-3/4,3/4,-6/7,6/7,-1,1,-3/2,3/2,-2,2,-3,3,-6,6$$

$$P\left(-1/84\right)=-5,952098$$

$$P\left(1/84\right)=-6,023243$$

$$P\left(-1/42\right)=-5,880385$$

$$P\left(1/42\right)=-6,020975$$

$$P\left(-1/28\right)=-5,785714$$

$$P\left(1/28\right)=-5,992347$$

$$P\left(-1/21\right)=-5,668934$$

$$P\left(1/21\right)=-5,936508$$

$$P\left(-1/14\right)=-5,372449$$

$$P\left(1/14\right)=-5,739796$$

$$\left(x-0,25\right)\left(84x^2+108x+24\right)=0$$

$$x=-1,-0,285714$$