T$13\mathrm{.}2.$ Derive an expression for voltage gain $\backslash ($ A$\_\{$v$\}=\backslash )\backslash ($ v$\_\{$o$\}/$ v$\_\{\backslash$text $\{$in $\}\}\backslash )$ of the circuit shown in Figure T$13\mathrm{.}2$ assuming that the summing$-$point constraint applies. $($There are both negative and positive feedback paths, but the resistances have been carefully selected so the circuit has net negative feedback and the summing$-$point constraint does apply.$)$

Figure T$13\mathrm{.}2$