Question 20: Perform the calculation \(\left(2 x^{2}-3 x y+y^{2}\right)(x+y)\)

\(\begin{aligned} &\left(2 x^{2}-3 x y+y^{2}\right)(x+y) \\ &=2 x^{2} \cdot x+2 x^{2} \cdot y-3 xy x-3 xy y+xy^{2}+y^{3} \\ &=2 x^{3}+2 x^{2} y-3 x^ {2} y-3 xy^{2}+xy^{2}+y^{3} \\ &=2 x^{3}-x^{2} y-2 xy^{2}+y^ {3} \end{aligned}\)