What is the Antiderivitive of xsin(7x)?

Do you have integration by parts?

If so:  ∫u dv  =  u·v -∫v du

Let u = x  -->  du = dx

Let dv = sin(7x)dx  -->  v = -(1/7)cos(7x) 

Substituting:  ∫xsin(7x)dx  =  -(x/7)cos(7x) - ∫-(1/7)cos(7x)dx

                     ∫xsin(7x)dx  =  -(x/7)cos(7x) +(1/7) ∫cos(7x)dx

                     ∫xsin(7x)dx  =  -(x/7)cos(7x) + (1/49)sin(7x) + C

Thanks Gino