Soln: Formula for a²+b² can be given by two types.
(i). a²+b² = (a+b)² - 2ab
= a²+2ab+b²-2ab
= a²+b²
=> LHS = RHS
Therefore, hence proved!
(ii). a²+b² = (a-b)² + 2ab
= a²-2ab+b²+2ab
=> LHS = RHS
Therefore, hence proved!
Hence, a²+b² = (a+b)² - 2ab
'OR'
a²+b² = (a-b)² + 2ab
Thank you. ☺️
hope it helps