Answer
$x^{3}+3x^{2}-37x+24$
Work Step by Step
$\left.\begin{array}{lllllll}
& & & & x^{2} & -5x & +3\\
& & & & & x & +8\\
& & & & -- & -- & --\\
& & & & 8x^{2} & -40x & +24\\
& & & x^{3} & -5x^{2} & +3x & \\
\hline & & & & & & \\
& & & x^{3} & +3x^{2} & -37x & +24
\end{array}\right. \qquad \begin{array}{l}
.\\
.\\
.\\
\leftarrow 8(x^{2}-5x+3)\\
\leftarrow x(x^{2}-5x+3)\\
\\
\leftarrow\text{combine }
\end{array}$