Case 1 :
Using (a+b)2=a2+b2+2ab
a=3p,b=3q
(3p+3q)2=(3p)2+(3q)2+2×3p×3q
(3p+3q)2=9p2+9q2+18pq
Case 2:
1010 can be written as (1000 + 10) and 990 can be written as (1000 - 10)
1010×990=(1000+10)×(1000−10)
Using the identity (a+b)(a−b)=a2−b2,
(1000+10)(1000−10) = 10002-102
= 1000000−100
= 999900
Case 3:
Using the identity, (a−b)2=a2+b2−2ab
Here, a=a2 and b=b2
(a2−b2)2=(a2)2+(b2)2−2a2b2
=a4+b4−2a2b2