`|x^2 - 2| = m^4 - m^2`
`->` \(\left[ \begin{array}{l}x^2 - 2 = m^4 - m^2\\x^2 - 2 = m^2 - m^4\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x^2 = m^4 - m^2 + 2 (l)\\x^2 = -m^4 + m^2 + 2\end{array} \right.\)
`-> x^2 = -m^4 + 2m^2 - m^2 + 2`
`-> x^2 = -m^2(m^2 - 2) - (m^2 - 2)`
`-> x^2 = (-m^2 - 1)(m^2 -2)`
`-> x = sqrt{(-m^2 - 1)(m^2 - 2)}`