Question

Multiply (in horizontal and vertical arrangement):

(6) (4 − p) (5 + p²)

Answer 1

(4 − p) (5 + p²)
Horizontal arrangement:
= (4 − p) × 5 + (4 − p) × p²
= 4 × 5 − p × 5 + 4 × p² − p × p²
= 20 − 5p + 4p² − p³

Vertical arrangement:
$\begin{array}{c}\begin{array}{ccccccc}& & & & 4& -& p\end{array}\\ \begin{array}{ccccccc}& & & \times & 5& +& p^2\end{array}\\ \overline{\begin{array}{ccccccc}& & & & 4p^2& -& p^3\end{array}}\\ \begin{array}{ccccccc}+20& -& 5p& & & & \end{array}\\ \underline{\overline{\begin{array}{ccccccc}20& -& 5p& +& 4p^2& -& p^3\end{array}}}\end{array}$