[tex]-4x^{-4}-3x^{-2}+1=0\\
-4x^{-4}-4x^{-2}+x^{-2}+1=0\\
-4x^{-2}(x^{-2}+1)+1(x^{-2}+1)=0\\
-(4x^{-2}-1)(x^{-2}+1)=0\\
4x^{-2}-1 =0 \vee x^{-2}+1=0\\
4x^{-2} =1 \vee x^{-2}=-1\\
x^{-2}=\frac{1}{4} \vee \frac{1}{x^2}=-1\\
\frac{1}{x^2}=\frac{1}{4}\\
x=-2 \vee x=2
[/tex]
