\(6\left(x+1\right)^2-2\left(x+1\right)^3+2\left(x-1\right)\left(x^2+x+1\right)=1\)
\(6.\left(x^2+2.x.1+1^2\right)-2.\left(x^3+3.x^2.1+3.x.1^2+1^3\right)+2.\left(x^3-1^3\right)=1\)
\(6x^2+12x+6-2x^3-6x^2-6x-2+2x^3-2=1\)
\(6x+2=1\)
\(6x=1-2\)
\(6x=-1\)
\(x=-1:6\)
\(x=-\frac{1}{6}\)