Kết quả của phép chia (7x^3 −7x +42) : (x^2 −2x+3) là: A. -7x +14

* Hướng dẫn giải

$\begin{array}{l}7{\text{x}}^3-7\text{x}+42\overline{)x^2-2\text{x}+3}\\ 7{\text{x}}^3-14{\text{x}}^2+21\text{x\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}}7x+14\\ \overline{14{\text{x}}^2-28x+42}\\ 14{\text{x}}^2-28\text{x}+42\\ \overline{0}\end{array}$

Vậy $\left(7x^3-7x+42\right):\left(x^2-2x+3\right)=7\text{x}+14$

Chọn C