Đáp án+Giải thích các bước giải:
Ta có:
`Q(x)=x^17-2020.x^16+2020x^15-2020.x^14+...+2020.x-1`
`\to Q(x)=x^17-2019.x^16-x^16+2019x^15+x^15-2019x^14-x^14+...+2019.x+x-1`
`\to Q(x)=x^16(x-2019)-x^15(x-2019)+x^14(x-2019)+...-x(x-2019)+x-1`
Với `x=2019`
`\to Q(x)=x^16(2019-2019)-x^15(2019-2019)+x^14(2019-2019)+...-x(2019-2019)+2019-1`
`\to Q(x)=x^{16}.0-x^{15}.0+x^{14}.0+...-x.0+2019-1`
`\to Q(x)=2019-1`
`\to Q(x)=2018`
Vậy với `x=2019` thì `Q(x)=2018`
