Đáp án đúng: D
Giải chi tiết:Ta có: \(\left\{ \begin{array}{l}\int\limits_{ - 1}^2 {[f\left( x \right) + 3g\left( x \right)]dx = 5} \\\int\limits_{ - 1}^2 {[ - f\left( x \right)} + g\left( x \right)]dx = - 1\end{array} \right.\)\( \Leftrightarrow \left\{ \begin{array}{l}\int\limits_{ - 1}^2 {f\left( x \right)dx} = 2\\\int\limits_{ - 1}^2 {g\left( x \right)dx} = 1\end{array} \right.\)Vậy \(\int\limits_{ - 1}^2 {\left[ {2f\left( x \right) + 3g\left( x \right) - 1} \right]dx} = 2\int\limits_{ - 1}^2 {f\left( x \right)dx} + 3\int\limits_{ - 1}^2 {g\left( x \right)dx} - \int\limits_{ - 1}^2 {dx} = 2.2 + 3.1 - 3 = 4\).Chọn D