(7a2+8b2-5c2) এর বর্গ
= (7a2+8b2-5c2)2
= {(7a2+8b2) - 5c2}2
= (7a2+8b2)2 - 2*(7a2+8b2)*5c2 + (5c2)2
= (7a2)2 + 2*7a2*8b2+ (8b2)2 - 10c2*(7a2+8b2) + (5c2)2
= 49a4 + 112a2b2 + 64b4 - 70c2a2 - 80b2c2 + 25c4
= 49a4 + 64b4 + 25c4 + 112a2b2 - 80b2c2 - 70c2a2 (Ans)