i. (ax + by)2
Here, A = ax and B = by
(ax + by)2 = (ax)2 + 2 × ax × by + (by)2 …. [(A + B)2 = A2 + 2AB + B2 ]
∴ (ax + by)2 = a2 x2 + 2abxy + b2 y2
ii. (7m – 4)2
Here, a = 7m and b = 4
(7m – 4)2 = (7m)2 – 2 × 7m × 4 + 42 …. [(a – b)2 = a2 – 2ab + b2 ]
∴ (7m – 4)2 = 49m2 – 56m + 16
iii. (x + 1/2)2
Here a = x and b = 1/2
iv. (a - 1/a)2
Here A = a and B = 1/a