Cho các đa thức sau:

* Hướng dẫn giải

a, $P\left(x\right)=x^3+3x^2+3x-2$;$Q\left(x\right)=-x^3-x^2-5x+2$

$P\left(x\right)+Q\left(x\right)=\left(x^3+3x^2+3x-2\right)+\left(-x^3-x^2-5x+2\right)$$\begin{array}{l}=\left(x^3-x^3\right)+\left(3x^2-x^2\right)+\left(3x-5x\right)+\left(-2+2\right)\\ =2x^2-2x\end{array}$

b, $P\left(x\right)-Q\left(x\right)=\left(x^3+3x^2+3x-2\right)-\left(-x^3-x^2-5x+2\right)$

$=\left(x^3+x^3\right)+\left(3x^2+x^2\right)+\left(3x+5x\right)+\left(-2-2\right)$

$=2x^3+4x^2+8x-4$

c,