Question

Solve:

x⁴ – 2x² – 3 = 0

Answer 1

x⁴ – 2x² – 3 = 0

${\displaystyle \Rightarrow }$ x⁴ – 3x² + x² – 3 = 0

${\displaystyle \Rightarrow }$ x²(x² – 3) + 1(x² – 3) = 0

${\displaystyle \Rightarrow }$ (x² – 3)(x² + 1) = 0

If x² – 3 = 0 or x² + 1 = 0

${\displaystyle \Rightarrow }$ x² = 3 or x² = –1  ...(Reject)

${\displaystyle \Rightarrow x=\pm \sqrt{3}}$