sage: _=var("a b c d x")
sage: forget()                 
sage: assume(b*(a*d-b*c)>0)    
sage: 1/((a+b*x)*(c+d*x)^(1/3))
1/((b*x + a)*(d*x + c)^(1/3))
sage: _.integrate(x)
ValueError: Computation failed since Maxima requested additional constraints;
using the 'assume' command before evaluation *may* help (example of 
legal syntax is 'assume(b*(a*d-b*c)
>0)', see `assume?` for more details)
Is b*(a*d-b*c)
    positive or negative?