Suppose
![](https://www.sarthaks.com/?qa=blob&qa_blobid=10826375449039542831)
On applying column operation C2 → C2 + C1
![](https://www.sarthaks.com/?qa=blob&qa_blobid=2380859725578590582)
On taking (a + b + c) common
![](https://www.sarthaks.com/?qa=blob&qa_blobid=15130915078449748383)
On applying row operation R2 → R2 - R1 and R3 → R3 - R1
![](https://www.sarthaks.com/?qa=blob&qa_blobid=17680441588959961315)
On taking (b - c) and (c - a) common
![](https://www.sarthaks.com/?qa=blob&qa_blobid=7546832512222360560)
= (a + b + c) (b – a) (c – a) (b – c)
Therefore, Δ = (a + b + c) (b – a) (c – a) (b – c)