$x=0\text{, }y\in \left(0,\frac{3^{\frac{6}{7}}}{3}\right)\cup \left(\frac{3^{\frac{6}{7}}}{3},\infty\right)\text{, }z=0$
$x=z\text{, }y=\frac{3^{\frac{6}{7}}}{3}\approx 0.8547514\text{, }z\in \mathrm{R}$
$x=0\text{, }y<-\frac{3^{\frac{6}{7}}}{3}\text{, }z=0$
$x=0\text{, }y\in \left(-\frac{3^{\frac{6}{7}}}{3},0\right)\text{, }z=0$