- Question 14 Consider the indefinite integral / x sin(3x) dac. 1 point We wish to use integration by parts. To this end, what are the best choices for the parts f and g' so that How Did I Do? x2 sin(3x) da = f(x)g'(x) da ? Answer: f (ac) = Q, 9(x) = Now compute the integral using integration by parts as many times as necessary. x sin (3x) da = + C, where C represents the integration constant. FORMATTING: Do not include the integration constant in your answer, as we have included it for you