The series is given by $\sum_{i=1}^{3}\left(x_{i}^{2}+x_{i}\right)$, so we need to find the values of $x_i^2 + x_i$ for $i=1,2,3$.
For $i=1$, we have $x_1^2 + x_1 = (-2)^2 + (-2) = 4 - 2 = 2$.
For $i=2$, we have $x_2^2 + x_2 = (-1)^2 + (-1) = 1 - 1 = 0$.
For
Show more…