ОДЗ:
0 \\ & \text{ } x+5>0 \\ & \text{ } x+5\ne 1 \end{cases}~~~\Rightarrow~~~ \begin{cases} & \text{ } \left[\begin{array}{ccc}x>3\\ x<-3\end{array}\right\\ & \text{ } ~~~x>-5 \\ & \text{ } ~~~x\ne -4 \end{cases} ~~\Rightarrow~~ \\ \Rightarrow~ x\in (-5;-4)\cup(-4;-3)\cup(3;+\infty) " alt=" \begin{cases} & \text{ } x^2-9>0 \\ & \text{ } x+5>0 \\ & \text{ } x+5\ne 1 \end{cases}~~~\Rightarrow~~~ \begin{cases} & \text{ } \left[\begin{array}{ccc}x>3\\ x<-3\end{array}\right\\ & \text{ } ~~~x>-5 \\ & \text{ } ~~~x\ne -4 \end{cases} ~~\Rightarrow~~ \\ \Rightarrow~ x\in (-5;-4)\cup(-4;-3)\cup(3;+\infty) " align="absmiddle" class="latex-formula">
![\log_7(x^2-9)=1\\ \log_7(x^2-9)=\log_77\\ x^2-9=7\\ x^2=16 \log_7(x^2-9)=1\\ \log_7(x^2-9)=\log_77\\ x^2-9=7\\ x^2=16](https://tex.z-dn.net/?f=+%5Clog_7%28x%5E2-9%29%3D1%5C%5C+%5Clog_7%28x%5E2-9%29%3D%5Clog_77%5C%5C+x%5E2-9%3D7%5C%5C+x%5E2%3D16+)
- не удовлетворяет ОДЗ
![x_2=4 x_2=4](https://tex.z-dn.net/?f=+x_2%3D4+)
Ответ: 4.