Đáp án:
`c)x^3-x^2+2/3x-4/27`
`d)-5x-8`
Giải thích các bước giải:
`c)(x^2+1/3x+1/9)(x-1/3)-(x-1/3)^2`
`=(x-1/3)[x^2+x. 1/3+(1/3)^2]-[x^2-2.x. 1/3+(1/3)^2]`
`=x^3-(1/3)^3-(x^2-2/3x+1/9)`
`=x^3-1/27-x^2+2/3x-1/9`
`=x^3-x^2+2/3x-(1/27+1/9)`
`=x^3-x^2+2/3x-4/27`
`d)(x-2)^3-x(x+1)(x-1)+6x(x-3)`
`=x^3-3.x^2 .2+3.x.2^2-2^3-x(x^2-1)+6x^2-18x`
`=x^3-6x^2+12x-8-x^3+x+6x^2-18x`
`=(x^3-x^3)+(-6x^2+6x^2)+(12x+x-18x)-8`
`=-5x-8`
