Question

factorise using a suitable method
$x ^{2} - 13x + 40$
​

Answer 1

${x}^{2} - 13x + 40 = 0$

${x}^{2} - 8x - 5x + 40 = 0$

$x(x - 8) - 5(x - 8) = 0$

$(x - 5)(x - 8) = 0$

$either \: \: (x - 5) = 0 \: or \: (x - 8) = 0$

$x = 5 \: or \: 8$