Cho \(\int\limits_0^3 {f\left( x \right)dx}  = 2\).

* Hướng dẫn giải

Ta có \(L = \int\limits_0^3 {\left[ {2f\left( x \right) - {x^2}} \right]dx}  = \int\limits_0^3 {2f\left( x \right)dx}  - \int\limits_0^3 {{x^2}dx}  = 2\int\limits_0^3 {f\left( x \right)dx}  - \left. {\frac{{{x^3}}}{3}} \right|_0^3 = 2.2 - \frac{{{3^3}}}{3} =  - 5\)