Đáp án:
d) (2x²-1/3xy+y²).(-3x³)
=-3x³.2x²+3x³.1/3xy-3x³.y²
=-6x^5+x^4y-3x³y²
e) (x²-2x+3).(x-4)
=(x.x²-x.2x+x.3)-(4.x²-4.2x+4.3)
=x³-2x²+3x-4x²+8x-12
=x³-6x²+11x-12
f) (2x³-3x-1).(5x+2)
=(5x.2x³-5x.3x-5x.1)+(2.1x³-2.3x-2.1)
=10x^4-15x²-5x+2x³-6x-2
=10x^4-15x²-11x+2x³-2