Câu 16. Nếu ∫03f(x)⋅dx=4\int_{0}^{3} f(x) \cdot d x=4∫03f(x)⋅dx=4 thì ∫033f(x)dx\int_{0}^{3} 3 f(x) d x∫033f(x)dx bằng
