49. Incorrect. The answer is false, not true. To solve ∫3xe^{x}dx let f(x) = 2x and g'(x) = e^{x}, then f'(x) = 2 and g(x) = e^{x}. Then ∫3xe^{x}dx = 3xe^{x} - ∫3e^{x}dx = 3xe^{x} - 3e^{x }+ c