( x2 - 5 ) . ( x2 - 1000 ) = 0
\(\Rightarrow\orbr{\begin{cases}x^2-5=0\\x^2-1000=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x^2=5\\x^2=1000\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=\mp\sqrt{5}\\x=\mp\sqrt{1000}\end{cases}}\)
\(\left(x^2-5\right)\left(x^2-10000\right)=0\Leftrightarrow\orbr{\begin{cases}x^2-5=0\\x^2-10000=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x^2=5\\x^2=10000\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=\pm\sqrt{5}\\x=\pm100\end{cases}}}\)