Question

4. Resuelve x al cuadrado - 4x - 21 = 0

AYUDA ​

Answer 1

${x}^{2} - 4x - 21 = 0$

$(x - 7)(x + 3) = 0$

$x - 7 = 0$

$x = 7$

$x + 3 = 0$

$x = - 3$