Question Number 155361 by Fikret last updated on 29/Sep/21
$${x}−\mathrm{4}{z}+\mathrm{8}{y}=\mathrm{7} \\ $$$$\mathrm{8}×+\mathrm{7}{z}−{y}=\mathrm{4} \\ $$$${x}^{\mathrm{2}} +{y}^{\mathrm{2}} −{z}^{\mathrm{2}} =? \\ $$
x-4z-8y-7-8-7z-y-4-x-2-y-2-z-2-