Answer
$-2x^3-6x^2-x-3$
Work Step by Step
The given expression, $
(4x-5x-3)(1+2x^2)
,$ is equivalent to
\begin{array}{l}\require{cancel}
(-x-3)(1+2x^2)
.\end{array}
Using $(a+b)(c+d)=ac+ad+bc+bd$ or the product of 2 binomials, the expression above is equivalent to
\begin{array}{l}\require{cancel}
-x(1)-x(2x^2)-3(1)-3(2x^2)
\\\\=
-x-2x^3-3-6x^2
\\\\=
-2x^3-6x^2-x-3
.\end{array}
