Question

solve using identites​

Answer 1

Answer:

use the identity

(a-b)^2 = a^2-2ab+b^2

Answer 2

Answer:

multiplying 2a^2 - 4b^2 + 28bc - 49c^2 by negative sign.

Therefore, - 2a^2 + 4b^2 - 28bc + 49c^2

= - 2a^2 + (4b^2 - 28bc + 49c^2). { using identity (a - b)^2 = a^2 - 2ab + b^2}

= - 2a^2 + (2b - 7b)^2