Bài làm :
a,
`(x-1)(x^2+x+1)`
`=(x-1)(x^2 +x.1+1^2)`
`=x^3-1^3`
`=x^3-1`
b,
`(x-3)(x^2+9+3x)`
`=(x-3)(x^2+3.x+3^2)`
`=x^3-3^3`
`=x^3-27`
c,
`(2-x)(4+2x+x^2)`
`=(2-x)(2^2+2.x+x^2)`
`=2^3-x^3`
`=8-x^3`
d,
`(2x-1)(4x^2+2x+1)`
`=(2x-1)[(2x)^2+2x.1+1^2]`
`=(2x)^3-1^3`
`=8x^3-1`
e,
`(x^2-y)(x^4+x^2y+y^2)`
`=(x^2-y)[(x^2)^2+x^2 . y+y^2]`
`=(x^2)^3-y^3`
`=x^6 - y^3`
f,
`(x^4+x^2+1)(x^2-1)`
`=(x^2-1)[(x^2)^2+x^2 . 1+1^2]`
`=(x^2)^3-1^3`
`=x^6-1`
g,
`(x^2y-yz)(x^4y^2+x^2y^2z+y^2z^2)`
`=(x^2y-yz)[(x^2y)^2+x^2y.yz+(yz)^2]`
`=(x^2y)^3-(yz)^3`
`=x^6y^3-y^3z^3`
h,
`(1/2x^2-4y)(1/4x^4+2x^2y+16y^2)`
`=(1/2x^2-4y)[(1/2x^2)^2+1/2x^2 . 4y+(4y)^2]`
`=(1/2x^2)^3-(4y)^3`
`=1/8x^6-64y^3`