86 : [2.(2X - 1)^2 - 7] + 42 = 2 . 3^2
=> 86 : [2.(2X - 1) ^ -5] + 42 = 18
=> 86 : [2.(2X - 1) ^ -5] = 18 - 42 = -24
=> [2.(2X - 1) ^ -5] = 86 : (-24) = -3,58333
=> (2X - 1) ^ -5 = -3,58333 : 2 = -1,79167
=> 2X^(-5) - 1^(-5) = -1,79167
=> 32X - 1 = -1,79167
=> 32X = -1,79167 + 1 = -0,79167
=> X = -0,79167 : 32 = -0,02474