`b) |2 - 3x^2| - |6 - x^2| = 0`
`<=> |2 - 3x^2| = |6 - x^2|`
`<=>` \(\left[ \begin{array}{l}2 - 3x^2 = 6 - x^2\\2 - 3x^2 = x^2 - 6\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}2x^2 = -4 (l)\\4x^2 = 8\end{array} \right.\)
`<=> x^2 = 2`
`<=> x = +-sqrt{2}`
`d) |x^2 - 2x| = |2x^2 - x - 2|`
`<=>` \(\left[ \begin{array}{l}x^2 - 2x = 2x^2 - x - 2\\2x - x^2 = 2x^2 - x - 2\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x^2 + x - 2 = 0\\3x^2 - 3x - 2 = 0\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x = 1\\x = -2\\x = \dfrac{3 + \sqrt{33}}{6}\\x = \dfrac{3 - \sqrt{33}}{6}\end{array} \right.\)
`f) |2x - 1| = |-5x - 2|`
`<=> |2x - 1| = |5x + 2|`
`<=>` \(\left[ \begin{array}{l}5x + 2 = 2x - 1\\5x + 2 = 1 - 2x\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}3x = -3\\7x = -1\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x = -1\\x = -\dfrac{1}{7}\end{array} \right.\)
