Question

find the products of the following using suitable identity
$(7a + 9b) \: (7a - 9b)$
​

Answer 1

Step-by-step explanation:

use

$(x + y)(x - y) = {x}^{2} - {y}^{2}$

you get

${(7a)}^{2} - (9b) {}^{2} = 49 {a }^{2} - 81 {b}^{2}$