1.
If Sr=2rxn(n+1)6r21yn2(2n+3)4r32nrzn3(n+1)S_r = \begin{vmatrix} 2r & x & n(n+1) \\ 6r^2-1 & y & n^2(2n+3) \\ 4r^3-2nr & z & n^3(n+1) \end{vmatrix}, then r=1nSr\sum_{r=1}^n S_r does not depend on -