ĐK : .....
$\Leftrightarrow \sqrt{x^2+9}-5-(\sqrt{x^2-7}-3)=0$
$\Leftrightarrow \frac{x^2-16}{\sqrt{x^2+9}+5}-\frac{x^2-16}{\sqrt{x^2-7}+3}=0$
$\Leftrightarrow (x^2-16)(\frac{1}{\sqrt{x^2+9}+5}-\frac{1}{\sqrt{x^2-7}+3})=0$
$\Leftrightarrow x^2-16=0$ Vì $\frac{1}{\sqrt{x^2+9}+5}=\frac{1}{\sqrt{x^2-7}+7}\neq \frac{1}{\sqrt{x^2-7}+3}\Rightarrow \frac{1}{\sqrt{x^2+9}+5}-\frac{1}{\sqrt{x^2-7}+3}\neq 0$
$\Leftrightarrow x=4....or....x=-4$( TMĐK)
Vậy ..........
~~~~$Amen$~~~~