Cho 0 ∫ − 3 f ( x ) d x = − 2024 và 0 ∫ − 3 g ( x ) d x = − 2025 . a) − 3 ∫ 0 f ( x ) d x = 2024 .
a) \(\int\limits_0^{ - 3} {f\left( x \right)dx} = - \int\limits_{ - 3}^0 {f\left( x \right)dx} = 2024\).
b) \(\int\limits_{ - 3}^0 { - 3g\left( x \right)dx} = - 3\int\limits_{ - 3}^0 {g\left( x \right)dx} = - 3.\left( { - 2025} \right) = 6075\).
c) \(\int\limits_{ - 3}^0 {\left[ {f\left( x \right) - g\left( x \right) + 1} \right]dx} = \int\limits_{ - 3}^0 {f\left( x \right)dx} - \int\limits_{ - 3}^0 {g\left( x \right)dx} + \left. x \right|_{ - 3}^0 = - 2024 + 2025 + 3 = 4\).
d) \(\left\{ \begin{array}{l}\int\limits_{ - 3}^0 {\left[ {mf\left( x \right) - ng\left( x \right)} \right]dx} = 2026\\\int\limits_{ - 3}^0 {\left[ { - nf\left( x \right) + mg\left( x \right)} \right]dx} = 2023\end{array} \right.\)\[ \Leftrightarrow \left\{ \begin{array}{l}m\int\limits_{ - 3}^0 {f\left( x \right)dx} - n\int\limits_{ - 3}^0 {g\left( x \right)dx} = 2026\\ - n\int\limits_{ - 3}^0 {f\left( x \right)dx} + m\int\limits_{ - 3}^0 {g\left( x \right)dx} = 2023\end{array} \right.\]\[ \Leftrightarrow \left\{ \begin{array}{l} - 2024m + 2025n = 2026\\2024n - 2025m = 2023\end{array} \right.\]\[ \Rightarrow m + n = 3\].
Đáp án: a) Đúng; b) Sai; c) Đúng; d) Sai.