Đáp án:
$\begin{array}{l}
E = \left( { - 4{x^2}} \right).\left( {{x^2} + 5x - 1} \right)\\
= - 4{x^4} - 20{x^3} + 4{x^2}\\
F = \left( {x + 3y} \right)\left( {2{x^2}y - 6x{y^2}} \right)\\
= 2{x^3}y - 6{x^2}{y^2} + 6{x^2}{y^2} - 18x{y^3}\\
= 2{x^3}y - 18x{y^3}\\
M = 2{\left( {x - 3} \right)^2} - \left( {2x - 1} \right)\left( {2x + 1} \right) + \left( {3x - 1} \right)\left( {x + 2} \right)\\
= 2\left( {{x^2} - 6x + 9} \right) - \left( {4{x^2} - 1} \right) + 3{x^2} + 6x - x - 2\\
= 2{x^2} - 12x + 18 - 4{x^2} + 1 + 3{x^2} + 5x - 2\\
= {x^2} - 7x + 17\\
N = {\left( {x + 2} \right)^2} - {\left( {x - 2} \right)^2} - \left( {x + 3} \right)\left( {x - 3} \right)\\
= {x^2} + 4x + 4 - \left( {{x^2} - 4x + 4} \right) - \left( {{x^2} - 9} \right)\\
= {x^2} + 4x + 4 - {x^2} + 4x - 4 - {x^2} + 9\\
= - {x^2} + 8x + 9
\end{array}$
