Recall the formula for integration by parts, which states that if ( f ) and ( g ) are differentiable functions, then the following holds. a) ( ∫ f(x) , dx = f(x) ⋅ g(x) - ∫ g(x) , dx ) b) ( ∫ f(x) , dx = f(x) + g(x) ) c) ( ∫ f(x) , dx = ∫ g(x) , dx ) d) ( ∫ f(x) , dx = f'(x) )