plz answer it........

Okay,
so,
The given expression is :
[tex]16{(a + b)}^{2} - 49 {(a - b)}^{2} [/tex]

As 16 is sqaure of 4 and 49 is square of 7, then this whole expression could also be written as

[tex] {{((4)(a + b))}}^{2} - {{((7)(a - b))}}^{2} [/tex]
Now,
as you might've notices by now that this expression is in the form of

[tex] {x}^{2} - {y}^{2} [/tex]
And there's an alzebric identity about it. That is
[tex] {x}^{2} - {y}^{2} = (x + y)(x - y)[/tex]
Now by using this alzebric identity. we're gonna split our expession as shown below:
[tex](4(a + b) + 7(a - b)) \times (4(a + b) - 7(a - b) \\ \\ = (4a + 4b + 7a - 7b) \times (4a + 4b - 7a + 7b) \\ = (11a - 3b)( 11b - 3a)[/tex]




By solving the last step i.e,
(11a-3b)(11b-3a)

we'll get,
121a^2 - 33ab -33b^2 -8ab

= 121a^2-33b^2 -41ab .