1)$x(5x^3+2)-2(\sqrt{2x+1}-1)=0 $$\Leftrightarrow 5x^4+2x-2\sqrt{2x+1}+2=0$
$\Leftrightarrow 5x^4+(\sqrt{2x+1}-1)^2=0$
$\Leftrightarrow \left\{ \begin{array}{l} 5x^4=0\\ (\sqrt{2x+1}-1)^2=0 \end{array} \right.\Leftrightarrow x=0./$
$2)$
$\Leftrightarrow 6-2x\sqrt{1-y^2}-2y\sqrt{1-z^2}-2z\sqrt{1-x^2}=0$
$\Leftrightarrow (x^2-2x\sqrt{1-y^2}+1-y^2)+....+....+3=0$
$\Leftrightarrow (x-\sqrt{1-y^2})^2+....+.......+3=0$
$\rightarrow $ PT vô nghiệm./