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%Problem 1, 4.5 (a)

(a) AR(1) PACF: 
\[
\phi_{kk} = \left \{ \begin{array}{ll}
         1 & k=0 \\
         \phi_1 = ? & k= 1 \\
         0   & k \geq 2 \\
\end{array}
\right. \]

%Problem 1, 4.5 (b)

(b) AR(1) PACF:
\[
\phi_{kk} = \left \{ \begin{array}{ll}
         1 & k=0 \\
         \phi_1 = ? & k= 1 \\
         0   & k \geq 2 \\
\end{array}
\right. \]

%Problem 2

AR(2) PACF:
\[
\phi_{kk} = \left \{ \begin{array}{ll}
         1 & k=0 \\
         \phi_1/(1-\phi_2) = ? & k= 1 \\
         \phi_2 = ?    & k= 2 \\
         0 & k \geq 3
\end{array}
\right. \]