Given the function f$($x$)=$f$($x$)=$ x$4+2$x$2+2$x$4+2$x$2+2.$ Find the x$-$value$($s$)$ of where the tangent line is horizontal.

$1,11,1$

$00$

$0\mathrm{.}5000,0\mathrm{.}50000\mathrm{.}5000,0\mathrm{.}5000$

$0\mathrm{.}50000\mathrm{.}5000$

$0\mathrm{.}5000$