Check my answer: Calculus

your endpoints are correct, however recall that x² means (x)².
[tex] \bf \begin{array}{cllll}
~~1\times [(-2)^2+8]\\\\
+1\times [(-1)^2+8]\\\\
+1\times [(0)^2+8]\\\\
+1\times [(1)^2+8]
\end{array}\implies
\begin{array}{llll}
~~4+8\\\\
+1+8\\\\
+0+8\\\\
+1+8
\end{array}\implies
\begin{array}{cll}
~12\\
+9\\
+8\\
+9\\
\text{\textemdash\textemdash\textemdash}\\
38
\end{array} [/tex]