Đáp án:
$\begin{array}{l}
a)4{x^3}y - 6{x^2}{y^2}\\
= 2{x^2}y\left( {2x - 3y} \right)\\
b)3{a^2}x + 6x + 15a{x^2}\\
= 3x\left( {{a^2} + 2 + 5ax} \right)\\
c)2mx - 4{m^2}xy + 6my\\
= 2m\left( {x - 2mxy + 3y} \right)\\
d)5{x^2}{y^4} - 10{x^4}{y^2} + 5{x^2}{y^4}\\
= 5{x^2}{y^2}\left( {{y^2} - 2{x^2} + 5{y^2}} \right)\\
= 5{x^2}{y^2}\left( {6{y^2} - 2{x^2}} \right)\\
= 10{x^2}{y^2}\left( {3{y^2} - {x^2}} \right)\\
e){x^2}{y^4} = {\left( {x{y^2}} \right)^2}
\end{array}$