a$-)$ Applying spatial domain Least Square $($LS$)$ estimation method, find the estimate hat$(f)(x,y)$ of the original $3-$bit gray$-$scale $33$ image $f(x,y)$ in the following image degradation model.

$\backslash$table$[[7\mathrm{.}17,10\mathrm{.}27,4\mathrm{.}86],[4\mathrm{.}58,5\mathrm{.}10,11\mathrm{.}10],[6\mathrm{.}29,3\mathrm{.}59,8\mathrm{.}13]]$

$=$

$\backslash$table$[[1,1,-2],[1,2,1],[-1,2,1],[c,,]]$

$\backslash$table$[[?,?,?$