Prove the following identities –

Question

Philoid · Accepted Answer

Let

Multiplying c, a and b to R₁, R₂ and R₃, we get

Recall that the value of a determinant remains same if we apply the operation R_i→ R_i + kR_j or C_i→ C_i + kC_j.

Applying R₁→ R₁ – R₂, we get

Applying R₁→ R₁ – R₃, we get

Applying C₂→ C₂ – C₁, we get

Applying C₃→ C₃ – C₁, we get

Expanding the determinant along R₁, we have

∴ Δ = 4abc

Thus,