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]
