Question

Expand using suitable identity-
(3a-7b-c) whole square

Answer 1

Dear student,
(3a –7b – c)²

Using identity,
[(a + b + c)² = a² + b² + c² + 2ab + 2bc + 2ca]

Here, a = 3a, b,= -7b & c = -c

(3a – 7b – c)²
= (3a)² + (-7b)²+ (-c)² + (2×3a×-7b) + (2×-7b×-c) + (2×-c×3a)
= 9a² + 49b² + c² –42ab + 14bc – 6ac

Regards