What is the sum of cubes of real roots of the equation x3−2x2−x+1=0?<spanclass=′latex−bold′>(A)</span> −6<spanclass=′latex−bold′>(B)</span> 2<spanclass=′latex−bold′>(C)</span> 8<spanclass=′latex−bold′>(D)</span> 11<spanclass=′latex−bold′>(E)</span> None of above geometry3D geometryalgebrafactorizationsum of cubes