Question

solve by factoring p^2-4p=21

Answer 1

$p^2-4p=21 \\ p^2 - 4p-21 = 0$ - set the equation equal to 0
$(p + 3)(p-7) = 0$ - factor
$p +3=0 \\ p=-3$ - one answer
$p-7 = 0 \\ p=7$ - Second answer