Đáp án:
$\begin{array}{l}
1) - 5x\left( {x - 3} \right)\left( {2x + 4} \right)\\
- \left( {x + 7} \right)\left( {x - 3} \right) + \left( {5x - 2} \right)\left( {3x + 4} \right)\\
= - 5x\left( {2{x^2} + 4x - 6x - 12} \right)\\
- \left( {{x^2} + 4x - 21} \right) + 15{x^2} + 20x - 6x - 8\\
= - 10{x^3} + 10{x^2} + 60x\\
- {x^2} - 4x + 21 + 15{x^2} + 14x - 8\\
= - 10{x^3} + 24{x^2} + 70x + 13\\
2)\left( {4x - 1} \right)\left( {3x + 1} \right) - 5{x^2}\left( {x - 3} \right)\\
- \left( {x - 4} \right)\left( {x - 3} \right) - 7\left( {{x^3} - 2{x^2} + x - 1} \right)\\
= 12{x^2} + 4x - 3x - 1 - 5{x^3} + 15{x^2}\\
- \left( {{x^2} - 7x + 12} \right) - 7{x^3} + 14{x^2} - 7x + 7\\
= - 12{x^3} + 40{x^2} + x - 6
\end{array}$
