試題詳解

5. Which of the following statement is TRUE?
(A) xf(x)dx = f(x)dx when f is continuous on [a, b].
(B) when f is continuous on [a, b] and f(x) ≥ 0 for all x ∈ [a, b].
(C) If f and g are differentiable and 0<f(x) ≤ g(x) on [a, b] then f'(x) ≤ g(x).
(D) If f and g are continuous and 0< f(x) ≤ g(x) on [a, b] then f(x)dx≤g(x)dx.