sub x value of -2.31 into: -1.38x^2 - 2.06x + 2.63
subsitute -2.31 where you see x and solve.
$$\begin{pmatrix}
-{\mathtt{1}}
\\
{\mathtt{38}}
\end{pmatrix}
{\mathtt{\,\times\,}}{\left(-{\mathtt{2.31}}\right)}^{{\mathtt{2}}}{\mathtt{\,-\,}}{\mathtt{2.06}}{\mathtt{\,\small\textbf+\,}}{\mathtt{2.63}}$$
$$\left(-{\mathtt{1.38}}\right){\mathtt{\,\times\,}}{\mathtt{5.336\: \!1}}{\mathtt{\,-\,}}{\mathtt{2.06}}{\mathtt{\,\times\,}}\left(-{\mathtt{2.31}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{2.63}}$$
$${\mathtt{\,-\,}}\left({\mathtt{7.363\: \!818}}\right){\mathtt{\,-\,}}{\mathtt{2.06}}{\mathtt{\,\times\,}}\left(-{\mathtt{2.31}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{2.63}}$$
$${\mathtt{\,-\,}}\left({\mathtt{7.363\: \!818}}\right){\mathtt{\,\small\textbf+\,}}\left({\mathtt{4.758\: \!6}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{2.63}}$$
$${\mathtt{\,-\,}}\left({\mathtt{2.604\: \!58}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{2.63}}$$
$$-{\mathtt{0.244\: \!58}}$$
sub x value of -2.31 into: -1.38x^2 - 2.06x + 2.63
subsitute -2.31 where you see x and solve.
$$\begin{pmatrix}
-{\mathtt{1}}
\\
{\mathtt{38}}
\end{pmatrix}
{\mathtt{\,\times\,}}{\left(-{\mathtt{2.31}}\right)}^{{\mathtt{2}}}{\mathtt{\,-\,}}{\mathtt{2.06}}{\mathtt{\,\small\textbf+\,}}{\mathtt{2.63}}$$
$$\left(-{\mathtt{1.38}}\right){\mathtt{\,\times\,}}{\mathtt{5.336\: \!1}}{\mathtt{\,-\,}}{\mathtt{2.06}}{\mathtt{\,\times\,}}\left(-{\mathtt{2.31}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{2.63}}$$
$${\mathtt{\,-\,}}\left({\mathtt{7.363\: \!818}}\right){\mathtt{\,-\,}}{\mathtt{2.06}}{\mathtt{\,\times\,}}\left(-{\mathtt{2.31}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{2.63}}$$
$${\mathtt{\,-\,}}\left({\mathtt{7.363\: \!818}}\right){\mathtt{\,\small\textbf+\,}}\left({\mathtt{4.758\: \!6}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{2.63}}$$
$${\mathtt{\,-\,}}\left({\mathtt{2.604\: \!58}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{2.63}}$$
$$-{\mathtt{0.244\: \!58}}$$
