Question

Expand the following:

(4a − 7b)²

Answer 1

(4a − 7b)²

Here, a = 4a, b = 7b

Thus,

(4a − 7b)² = (4a)² − 2(4a) × (7b) + (7b)²   ...[Using (a ± b)² = a² ± 2ab + b²]

16a² − 2(28ab) + 49b²

∴ 16a² − 56ab + 49b²