$11\mathrm{.}1-6$ Using only the z$-$transforms of Table $11\mathrm{.}1,$

determine the z$-$transform of each of the

following signals:

$($a$)2$n$+1$dots $1[2^(-$n$)$cos$((\backslash$pi $)/(3)$n$)]$u$[$n$-1]$

$($e$)$ n$\backslash$gamma $^($n$)$u$[$n$-1]$