1323
1. \( H = \begin{pmatrix} 0 & c & c & c \\ c & 0 & c & c \\ c & c & 0 & c \\ c & c & c & 0 \end{pmatrix} \)
2. \( E = 3c,-c,-c,-c \). If \(c\) is added to the diagonal then \( \tilde{E} = 4c,0,0,0 \).
3. \( H = c \hat{D} + c \hat{D}^{-1} + c \hat{D}^2 \)
4.\( H = 2c \cos(p) + c \cos(2p) \)
6. \( E = 2c + c_{\perp} , -c_{\perp}, -2c + c_{\perp}, -c_{\perp} \)