Considering
![](https://www.sarthaks.com/?qa=blob&qa_blobid=11339872271966820851)
On applying C2 → C2 - 2C1 - 2C3
![](https://www.sarthaks.com/?qa=blob&qa_blobid=6176941829806948179)
Take -(a2 + b2 + c2) common from C2
![](https://www.sarthaks.com/?qa=blob&qa_blobid=7948545821966621149)
On applying R2 → R2 - R1, and R3 → R3 - R1
![](https://www.sarthaks.com/?qa=blob&qa_blobid=14481757143629709416)
= – (a2 + b2 + c2) (a – b) (c – a) [(– (b + a)) (– b) – (c) (c + a)]
= (a – b) (b – c) (c – a) (a + b + c) (a2 + b2 + c2)
= R.H.S
Hence, proved.