Question
If $x + 2$ is a factor of $x^2 + mx + 14,$ then $m =$
✓
Answer
If $x + 2$ is a factor of $x^2 + mx + 14,$
then at $x = -2,$
$x^2 + mx + 14 = 0$
$i.e. (-2)^2 + m(-2) + 14 = 0$
$4 - 2m + 14 = 0$
$2m = 18$
$m = 9$
then at $x = -2,$
$x^2 + mx + 14 = 0$
$i.e. (-2)^2 + m(-2) + 14 = 0$
$4 - 2m + 14 = 0$
$2m = 18$
$m = 9$
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