Question

Show step by step how to use the horizontal method to multiply the two polynomials (3a2 + 5a - 2)(5a2 – 3a + 4).

Answer 1

Given:

$(3a^2+5a-2)(5a^2-3a+4)$

Horizonatal method:

$\begin{gathered} (3a^2+5a-2)(5a^2-3a+4) \\ =3a^2(5a^2-3a+4)+5a(5a^2-3a+4)-2(5a^2-3a+4) \\ =15a^4-9a^3+12a^2+25a^3-15a^2+20a-10a^2+6a-8 \\ =15a^4+16a^3-13a^2+26a-8 \end{gathered}$