Thực hiện các phép nhân hai đa thức sau: -2,5x^4 + 0,5x^2 + 1 và 4x^3 - 2x + 6.

Ta đặt tính nhân như sau:

\(\begin{array}{l}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\begin{array}{*{20}{c}}{}\\ \times \\{}\end{array}\,\,\,\,\,\begin{array}{*{20}{c}}{ - 2,5{x^4} + 0,5{x^2} + 1}\\{}\\{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,4{x^3} - 2x + 6}\end{array}\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\overline {\, - 15{x^4}\,\,\,\,\,\,\,\,\,\, + \,\,3{x^2}\,\,\,\,\,\,\,\,\,\, + 6} \\ + \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,5{x^5}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, - {x^3}\,\,\,\,\,\,\,\,\,\,\,\,\, - 2x\\\,\,\,\, - 10{x^7} + 2{x^5}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, + 4{x^3}\\\overline {\,\,\, - 10{x^7} + 7{x^5} - 15{x^4} + 3{x^3} + 3{x^2} - 2x + 6\,} \end{array}\)