Đáp án:
$\begin{array}{l}
a){x^2} - 3x + 2\\
= {x^2} - 2x - x + 2\\
= x\left( {x - 2} \right) - \left( {x - 2} \right)\\
= \left( {x - 2} \right)\left( {x - 1} \right)\\
b){x^2} + x - 6\\
= {x^2} + 3x - 2x - 6\\
= x\left( {x + 3} \right) - 2\left( {x + 3} \right)\\
= \left( {x + 3} \right)\left( {x - 2} \right)
\end{array}$