Find the linear approximation of the function f$($x$,$ y$,$ z$)=$

x$2+$ y$2+$ z$2$

$$at $(3,6,2)$ and use it to approximate the number$$

$3\mathrm{.}032+5\mathrm{.}982+1\mathrm{.}992$

$.($Round your answer to five decimal places.$)$

f$(3\mathrm{.}03,5\mathrm{.}98,1\mathrm{.}99)$