Solve: x4 – 3x2 + 2 = 0.

Answer.

Given equation is x4 - 3x2 + 2  = 0

Put   x2 = a

 a2 – 3a + 2 = 0

a2 – 2a – a + 2 = 0

a(a – 2) – 1 (a – 2) = 0

(a – 2 ) (a – 1) = 0

  a – 2 = 0   

OR  

a – 1 = 0

∴ a = 2
 ∴ a = 1

Re substituting the value of  a = x2

∴ x2 = 2
 x2 = 1

∴ x = ± √2  
 ∴ x = ± 1

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