LHS
= (2a + 3b)2 – (2a – 3b)2
= [(2a)2 + 2(2a) (3b) + (3b)2] – [(2a)2 – 2(2a) (3b) + (3b)2] (Using identity I and II)
= (4a2 + 12ab + 9b2) – (4a2 – 12ab + 9b2)
= 4a2 + 12ab + 9b2 – 4a2 + 12ab – 9b2
= (4a2 – 4a2) + (12ab + 12ab) + (9b2 – 9b2)
= 0 + 24ab + 0
= 24 ab
= RHS