Đáp án+Giải thích các bước giải:
`a)(x^2-x+1)(x+1)`
`=x^3-x^2+x+x^2-x+1`
`=x^3+(-x^2+x^2)+(x-x)+1`
`=x^3+1`
`b)(x-y)(x^2+xy+y^2)`
`=x^3+x^2 y+xy^2-x^2 y -xy^2-y^3`
`=x^3+(x^2 y-x^2 y)+(xy^2-xy^2)-y^3`
`=x^3-y^3`
`c)(x-2)(x^3+2x^2-x+1)`
`=x^4+2x^3-x^2+x-2x^3-4x^2+2x-2`
`=x^4+(2x^3-2x^3)+(-x^2-4x^2)+(x+3x)-2`
`=x^4-5x^2+4x-2`
`d)(2x^{2n}+x^{2n+1})(x^{1-2n}-2x^{2-2n})`
`=2x^{2n}*x^{1-2n}-2x^{2n}*2x^{2-2n}+x^{2n+1}*x^{1-2n}-x^{2n+1}*2x^{2-2n}`
`=2x^{2n+1-2n}-4x^{2n+2-2n}+x^{2n+1+1-2n}-2x^{2n+1+2-2n}`
`=2x^1-4x^2+x^2-2x^3`
`=2x^3-3x^2+2x`