Applying, C₂→C₂ + C₁

Taking, (a + b + c) common,

Applying R₂→R₂ – R₁, and R₃→R₃ – R₁

Taking, (b – c) and (c – a) common,

= (a + b + c)(b – a)(c – a)(b – c)

So, Δ = (a + b + c)(b – a)(c – a)(b – c)