\(\left(x+1\right)^3+\left(x-2\right)^3=\left(2x-1\right)^3\)
\(\Leftrightarrow2x^3-3x^2-3x+2=0\)
\(\Leftrightarrow\left(2x^3-4x^2\right)+\left(x^2-2x\right)+\left(-x+2\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(2x^2+x-1\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(\left(2x^2+2x\right)+\left(-x-1\right)\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(x+1\right)\left(2x-1\right)=0\)
\(\Leftrightarrow\left[\begin{matrix}x=2\\x=-1\\x=\frac{1}{2}\end{matrix}\right.\)