Question

Check my answer: Calculus

Answer 1

your endpoints are correct, however recall that x² means (x)².

$\bf \begin{array}{cllll} ~~1\times [(-2)^2+8]\\\\ +1\times [(-1)^2+8]\\\\ +1\times [(0)^2+8]\\\\ +1\times [(1)^2+8] \end{array}\implies \begin{array}{llll} ~~4+8\\\\ +1+8\\\\ +0+8\\\\ +1+8 \end{array}\implies \begin{array}{cll} ~12\\ +9\\ +8\\ +9\\ \text{\textemdash\textemdash\textemdash}\\ 38 \end{array}$