We want to apply integration by parts method. For the integral ∫x sin 3(x) dx the outcome of the IBP (integration by parts) method is
a. 1/3 sin (3x) – 1/3 x cos (3x) + C
b. 1/9 sin (3x) – 1/9 x cos (3x) + C
c. 1/9 sin (3x) - 1/3 x cos (3x) + C
d. 19 cos (3x) – 1/3 sin (3x) + C