Giải thích các bước giải:
\(\begin{array}{l}
a)3x(x - 2) - 5x(1 - x) - 5({x^2} - 3)\\
= 3{x^2} - 6x - 5x + 5{x^2} - 5{x^2} + 15\\
= 3{x^2} - 11x + 15\\
b.(7x - 3)(2x + 1) - (5x - 2)(x + 4) - 9{x^2} + 17x\\
= 14{x^2} - 6x + 7x - 3 - 5{x^2} - 20x + 2x + 8 - 9{x^2} + 17x\\
= 5\\
c)\left( {6x - 5} \right)\left( {x + 8} \right) - \left( {3x - 1} \right)\left( {2x + 3} \right) - 9\left( {4x - 3} \right)\\
= 6{x^2} - 5x + 48x - 40 - 6{x^2} - 9x + 2x + 3 - 36x + 27\\
= - 10\\
d) - 3x{(x + 2)^2} + (x + 3)(x - 1)(x + 1) - {(2x - 3)^2}\\
= - 3x\left( {{x^2} + 4x + 4} \right) + \left( {x + 3} \right)\left( {{x^2} - 1} \right) - 4{x^2} + 12x - 9\\
= - 3{x^3} - 12{x^2} - 12x + {x^3} - x + 3{x^2} - 3 - 4{x^2} + 12x - 9\\
= - 2{x^3} - 13{x^2} - x - 12
\end{array}\)
