$$2 { x }^{ 2 } + { y }^{ 2 } +8 { z }^{ 2 } -2 \sqrt{ 2xy } +4 \sqrt{ 2 { y }^{ 2 } } -8xz$$
$2\left(x-2z\right)^{2}+y^{2}+4\sqrt{2}|y|-2\sqrt{2xy}$
$4x-8z-\sqrt{\frac{2}{xy}}y$
