Respuesta :

RVADAMARAJANCHITHRA

Answer:

49a^2 - 126ab + 81 ^2

Step-by-step explanation:

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

So, to solve this.

(7a-9b)(7a-9b) = 49a^2 - 126ab + 81b^2

Hope this helps