dy/dx = y3xcos2xS 1/y dy = S 3xcos2x dx, let u=x, u'=1, v'=cos2x, v=1/2sin2xIf I = 3xcos2x dx, then I = uv - S u'vln y = 3x(1/2sin2x) - S 3(1/2sin2x) dx = 3/2xsin2x - 3/2(-1/2cos2x) + c =3/2xsin2x + 3/4cos2x + cwhen x = π/6, y = e,lne = 3(π/6)/2sin2π/6 + 3/4cos2π/6 + c1 = π√3/8 + 3/8 + cc = 5/8 - π√3/8y = e^(3/2xsin2x + 3/4cos2x + 5/8 - π√3/8)