Question

Find the product:
(x³ − 5x² + 3x + 1) × (x³ − 3)

Answer 1

By horizontal method:

$$\begin{gathered} (x^3-5x^2+3x+1)\times (x^2-3) \\ =x^2(x^3-5x^2+3x+1)-3(x^3-5x^2+3x+1) \\ =x^5-5x^4+3x^3+x^2-3x^3+15x^2-9x-3 \\ =x^5-5x^4+16x^2-9x-3 \end{gathered}$$