Question:
Find the product:
(x2 − 5x + 8) × (x2 + 2x − 3)
Solution:
By horizontal method:
$\left(x^{2}-5 x+8\right) \times\left(x^{2}+2 x-3\right)$
$=x^{2}\left(x^{2}-5 x+8\right)+2 x\left(x^{2}-5 x+8\right)-3\left(x^{2}-5 x+8\right)$
$=x^{4}-5 x^{3}+8 x^{2}+2 x^{3}-10 x^{2}+16 x-3 x^{2}+15 x-24$
$=x^{4}-3 x^{3}-5 x^{2}+31 x-24$