Đáp án:
$\begin{array}{l}
K = {x^2} + 27x + 12\left( {x + 27} \right)\\
= x\left( {x + 27} \right) + 12\left( {x + 27} \right)\\
= \left( {x + 27} \right)\left( {x + 12} \right)\\
H = {x^2} + 2019x - {y^2} - 2019y\\
= \left( {{x^2} - {y^2}} \right) + \left( {2019x - 2019y} \right)\\
= \left( {x - y} \right)\left( {x + y} \right) + 2019\left( {x - y} \right)\\
= \left( {x - y} \right)\left( {x + y + 2019} \right)
\end{array}$