$7\mathrm{.}14$ In a conducting medium H$=$yzax$+2($x$+1)$yzay$($x$+1)$z$2$az$$A$/$mH $=$ y z a$\_$x $+2($x $+1)$ y z a$\_$y $-($x $+1)$ z$^2$ a$\_$z $\backslash ,\backslash$text$\{$A$/$m$\}$H$=$yzax$+2($x$+1)$yzay$($x$+1)$z$2$az$$A$/$m