Bài 1. a) x³+9x²+27x+27=(x+3)³
b) 3√3x³+18x²+12√3x+8=(√3x+2)³
c) 27x³+27x²+9x+1=(3x+1)³
d) x³+3√2x²+6x+2√2=(x+√2)³
Bài 3. a) P=x³+3x²+3x+1=(x+1)³=100³=1000000
b) Q=(x³+6x²+12x+8)+3(x²+4x+4)y+3(x+2)y²+y³=(x+2)³+3(x+2)²y+3(x+2)y²+y³=(x+2+y)³=10³=1000
Bài 5. a) 27x³-27x²+9x-1=(3x-1)³
b) 3√3x³-18x²+12√3x-8=(√3x-2)³
Bài 7. A=(x+2)³-(x-2)³-12x²=x³+6x²+12x+8-(x³-6x²+12x-8)-12x²=12x²-12x²=0
Bài 8. x³-3x²+3x-1=(x-1)³=10³=1000
Bài 9. x³+3/10x²+3/100x+1/1000=(x+1/10)³=1