Question

8. Use the identity (x + a)(x + b) = x2 + (a+b)x + ab to find the following products.
(i) (x+3)(x + 7)
(ii) (4x + 5)(4x + 1)

​

Answer 1

$(i) \: x {}^{2} + (7 + 3)x + (7)(3) \\ x {}^{2} + 10x + 21$

$(ii) \: (4x) {}^{2} + (5 + 1)4x + (5)(1) \\ 16x {}^{2} + 24x+ 5$

Answer 2

Hello Friend!

____________________

(i) ( x + 3 )( x + 7 )

= x² + ( 3 + 7 )x + 3 * 7

= x² + 3x + 7x + 21

= x² + 10x + 21

(ii) ( 4x + 5 )( 4x + 1 )

= (4x)² + ( 5 + 1 )4x + 5 * 1

= 16x² + 20x + 4x + 5

= 16x² + 24x + 5

_______________________________

Hope This Helps You!