Let Δ = Applying Row Transformations R 2 → R 2 – R 1 Δ = R 3 → R 3 – R 1 Δ = Taking (β – α)(γ – α) from R 2 and R 3 respectively Δ = (β – α) (γ – α) Applying R 3 → R 3 – R 2 , we have Δ = (β – α) (γ – α) Expanding along R 3 , we have Δ = (β – α) (γ – α) [0 (α 2 × (-1) – (β + γ) × (β + γ) – (γ – β)((-1) × α – 1 × (β + γ) + 0 (α × (β + γ) – 1 × α 2 ) Δ = (β – α) (γ – α) [0 – (γ – β)( - α - β – γ) + 0] Δ = (β – α) (γ – α) (γ – β) (α + β + γ) Δ = (α – β) (β – γ) (γ – α) (α + β + γ)