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