Answer
$x^{4}+2x^{3}-10x=(x-3)(x^{3}+5x^{2}+15x+35)+105$
Work Step by Step
Using synthetic division,
$\left.\begin{array}{l}
3\lfloor \\ \\ \\ \end{array}\right.\begin{array}{rrrrr}
1 &2 &0 &-10&0 \\\hline
&3 &15 &45&105 \\\hline
1 &5 &15 &35&105 \end{array}$
$Q(x)=x^{3}+5x^{2}+15x+35,\quad R(x)=105$
In the form $P(x)=D(x)\cdot Q(x)+R(x),$
$x^{4}+2x^{3}-10x=(x-3)(x^{3}+5x^{2}+15x+35)+105$
