Question

(factories) plz tell​

Answer 1

Answer:

✏Factorization :-

$= > {x}^{2} - 4x - 21 \\ = > {x}^{2} - 7x + 3x - 21 \\ = > x(x - 7) + 3(x - 7) \\ = > (x - 7)(x + 3)$

✏Now x equals to :-

$= > x - 7 = 0 \\ = > x = 7$

✏or

$= > x + 3 = 0\\ = > x = - 3$

⭐Hope it helps you⭐

Answer 2

Question:-

${x}^{2} - 4x - 21$

Solution:-

${x}^{2} - 4x - 21$

$= {x}^{2} - (7 - 3)x - 21$

$= {x}^{2} - 7x + 3x - 21$

$= x(x - 7) + 3(x - 7)$

$= (x + 3 ) (x - 7)$

Now,

(x + 3) = 0

=> x = - 3

And,

(x - 7) = 0

=> x = 7

Therefore, Either x = - 3 or 7