Question

answer my question . see below.
$2 {(a + b)}^{2} - 9(a + b) - 5$

Answer 1

${\large{\sf{\underline{\underline{\green{Solution \ :}}}}}}$

$\sf\green{2 \ ( \ a + b )^2 - 9 \ ( \ a + b \ ) - 5}$

${\boxed{\sf{( \ x + y \ )^2 \ = \ x^2 + y^2 + 2xy}$

$\sf\green{= \ 2 \ [ \ (a)^2 + (b)^2 + 2(x)(y) \ ] - 9 \ ( \ a + b \ ) - 5}$

$\sf\green{= \ 2 \ ( \ a^2 + b^2 + 2ab \ ) - 9 \ ( \ a + b \ ) - 5}$

${\boxed{\sf{\green{= \ 2a^2 + 2b^2 + 4ab - 9a - 9b - 5}}}}$

$\large\red \star$$\large\bold\red{TheSia}$$\large\red \star$

Answer 2

let a + b = x then
2 x ^2 - 9 x - 5
= 2 x^2 - 10x + x - 5
= 2x ( x - 5 ) + 1 ( x - 5 )
= ( x - 5 ) ( 2x + 1 )
= ( a + b - 5 ) { 2 ( a + b ) + 1 }
= ( a + b - 5 ) (2a + 2b+ 1 )