Thực hiện các phép tính: (3x^3 +10x^2 -1) : (3x+1)

* Hướng dẫn giải

$\begin{array}{l}3{\text{x}}^3+10{\text{x}}^2-1\\ =3{\text{x}}^3+x^2+9{\text{x}}^2+3\text{x}-3\text{x}-1\\ =x^2\left(3\text{x}+1\right)+3x\left(3\text{x}+1\right)-\left(3\text{x}+1\right)\\ =\left(x^2+3\text{x}-1\right)\left(3\text{x}+1\right)\end{array}$

Vậy $\left(3x^3+10x^2-1\right):\left(3x+1\right)=x^2+3\text{x}-1$