7.050. $\log _{2} \frac{x-5}{x+5}+\log _{2}\left(x^{2}-25\right)=0$.
## Solution.

Domain of definition: $\frac{x-5}{x+5}>0$ or $x \in(-\infty ;-5) \cup(5 ; \infty)$.

We have $\log _{2} \frac{(x-5)\left(x^{2}-25\right)}{x+5}=0,(x-5)^{2}=1$, from which $x-5=-1$ or $x-5=1$. Then $x_{1}=4, x_{2}=6 ; x_{1}=4$ does not fit the domain of definition.

Answer: 6.