Question

Solve:

x⁴ – 10x² + 9 = 0

Answer 1

x⁴ – 10x² + 9 = 0

`=>` x⁴ – 9x² – x² + 9 = 0

`=>` x²(x² – 9) – 1(x² – 9) = 0

`=>` (x² – 9)(x² – 1) = 0

If x² – 9 = 0 or x² – 1 = 0

`=>` x² = 9 or x² = 1

`=>` x = ±3 or x = ±1