Câu 37:

Cho $\int\limits_{ - 2}^1 {f(x)\,dx = 1,\,\,\int\limits_{ - 2}^1 {g(x)\,dx = - 2} }$. Tính $\int\limits_{ - 2}^1 {\left( {1 - f(x) + 3g(x)} \right)} \,dx$.