(x-6) (x-3) ^3=(x+3) (x-6) ^3x^4-15x^3+81x^2-189x+162-x^4+15x^3-54x^2-108x+648=081x^2-189x+162-54x^2-108x+648=027x^2-297x+810=0D=(-297) ^2-4*27*810=88209-87480=729x1=(27- (-297) / (2*27)=324/54=6x2=(-27- (-297) / (2*27)=270/54=5