Question

Solve the following according to the given instructions evaluate using suitable identities.
(2a+7) (2a-7)

Answer 1

$(2a + 7)(2a - 7) = (2a - 7) ^{2}$

$identity = (a - b) ^{2} = {a}^{2} - 2ab + {b}^{2}$

$= 2a ^{2} - 2 \times 2a \times 7 + (7 )^{2}$

$= 4 {a}^{2} - 28a + 49$