d: \(=\left(3+3^2+3^3+3^4\right)+3^4\left(3+3^2+3^3+3^4\right)+...+3^{996}\left(3+3^2+3^3+3^4\right)\)
\(=120\left(1+3^4+...+3^{996}\right)⋮120\)
c: \(=\left(3+3^2\right)+3^2\left(3+3^2\right)+...+3^{1996}\left(3+3^2\right)\)
\(=12\left(1+3^2+...+3^{1996}\right)⋮12\)
\(D=\left(3+3^2+3^3\right)+3\left(3+3^2+3^3\right)+...+3^{1995}\left(3+3^2+3^3\right)\)
\(=39\left(1+3+...+3^{1995}\right)⋮39\)
b: \(=2\left(1+2\right)+2^3\left(1+2\right)+...+2^{2003}\left(1+2\right)\)
\(=3\left(2+2^3+...+2^{2003}\right)⋮3\)
\(B=2\left(1+2+2^2\right)+2^4\left(1+2+2^2\right)+...+2^{2002}\left(1+2+2^2\right)\)
\(=7\left(2+2^4+...+2^{2002}\right)⋮7\)
