\(6\left(x+1\right)^2-2\left(x+1\right)^3+2\left(x^2+x+1\right)\left(x-1\right)=1\)
\(\Leftrightarrow6\left(x^2+2x+1\right)-2\left(x^3+3x^2+3x+1\right)+2\left(x^3-1\right)=1\)
\(\Leftrightarrow6x^2+12x+6-2x^3-6x^2-6x-2+2x^3-2=1\)
\(\Leftrightarrow6x=-1\)
\(\Leftrightarrow x=-\dfrac{1}{6}\)