25. $2 \log _{x} a+\log _{a x} a+3 \log _{a^{2} x} a=0$.
25. Transitioning to logarithms with base $a(a \neq 1)$, we get

$$
\frac{2}{\log _{a} x}+\frac{1}{1+\log _{a} x}+\frac{3}{2+\log _{a} x}=0 . \text { From which } x_{1}=a^{-\frac{1}{2}} ; \quad x_{2}=a^{-\frac{4}{3}}
$$