\((a^4+b^4)x^2-2(a^2+b^2)x+1=0\)
\((a^4+b^4)x^2-2(a^2+b^2)x=-1\)
\(x^2-\frac{2(a^2+b^2)}{a^4+b^4}x=-\frac{1}{a^4+b^4}\)
\(x^2-\frac{2(a^2+b^2)}{a^4+b^4}x+(\frac{a^2+b^2}{a^4+b^4})^2=-\frac{1}{a^4+b^4}+(\frac{a^2+b^2}{a^4+b^4})^2\)
\((x-\frac{a^2+b^2}{a^4+b^4})^2=-\frac{1}{a^4+b^4}+(\frac{a^2+b^2}{a^4+b^4})^2 |±\sqrt{~~}\)
1.)
\(x-\frac{a^2+b^2}{a^4+b^4}=\sqrt{-\frac{1}{a^4+b^4}+(\frac{a^2+b^2}{a^4+b^4})^2} \)
\(x_1=\frac{a^2+b^2}{a^4+b^4}+\sqrt{-\frac{1}{a^4+b^4}+(\frac{a^2+b^2}{a^4+b^4})^2}\)
2.)
\(x-\frac{a^2+b^2}{a^4+b^4}=-\sqrt{-\frac{1}{a^4+b^4}+(\frac{a^2+b^2}{a^4+b^4})^2} \)
\(x_2=\frac{a^2+b^2}{a^4+b^4}-\sqrt{-\frac{1}{a^4+b^4}+(\frac{a^2+b^2}{a^4+b^4})^2}\)
\(\sqrt{(\frac{a^2+b^2}{a^4+b^4})^2-\frac{1}{a^4+b^4}}=\sqrt{(\frac{a^2+b^2}{a^4+b^4})^2-\frac{a^4+b^4}{(a^4+b^4)^2}}\\=\sqrt{\frac{a^4+2a^2b^2+b^4-a^4-b^4}{(a^4+b^4)^2}}=\sqrt{\frac{2a^2b^2}{(a^4+b^4)^2}}=\frac{|a|\cdot |b|\sqrt{2}}{|a^4+b^4|}\)