Hi
2x⁴-7x²-4           |Let X = x^2
2X^2 - 7X - 4 = 0
(2X + 1)(X -  4)
             0r
  X = -1/2          X = 4
  x^2 = -.5        x^2 = 4
  x = ± i√.5         x = ± 2

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