Đáp án:
a) (3x-2)²+(2x+5)²-(3x+4).(3x-4)
=(3x-2)²+(2x+5)²- 9x²+16
= 9x²-12x+4+4x²+20x+25-9x²+16
= (9x²+4x²-9x²)+(-12x+20x)+(4+25+16)
= 4x²+8x+45
b) (3x+2).(9x² - 6x+4) + (5-3x).(25+15+9x²)-9
=27𝑥³−18𝑥²+12𝑥+18𝑥²−12𝑥+8+(5-3x)(40+9x²)-9
=27𝑥³−18𝑥²+18𝑥²+12𝑥−12𝑥+8+200+45𝑥²-120x-27𝑥³-9
=(27𝑥³-27𝑥³)+(−18𝑥²+18𝑥²+45𝑥²)+(12𝑥−12𝑥-120x)+(8+200-9)
=45𝑥²-120x+199
c) (x-3)³ - (x+2).(x-2).(x-1)
= (x-3)³ - (x²-4)(x-1)
= x³-9x²+27x-27 - x³+x²+4x-4
= (x³- x³)+(-9x²+x²)+(27x+4x)-(27+4)
=-8x²+31x-31