Question

$x {}^{2} + 4x - 21$
​

Answer 1

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

x = 3
OR
x=(-7)

Answer 2

$\huge\blue{heya!!}$

$the \: answer \: is \: ...... \\ \\ x = 7 \: \: or \: \: \: x = - 3 \\ \\ but \: ....x = - 3 \: is \: no \: possible... \\ \\ so... \: \: x = 7$