Question

Find the product:
(x³ − y³) × (x² + y²)

Answer 1

By horizontal method:

$$\begin{gathered} (x^3-y^3)\times (x^2+y^2) \\ =x^3(x^2+y^2)-y^3(x^2+y^2) \\ =x^5+x^3{y}^2-x^2{y}^3-y^5 \\ =\left(x^5-y^5\right)+x^2{y}^2\left(x-y\right) \end{gathered}$$