1. The problem statement, all variables and given/known data The equation of the tangent to the curve f(x)=ax^3+bx at the point of contact (-1;3) is y-x-4=0. Calculate the values of a and b 2. Relevant equations y-y1=m(x-x1) 3. The attempt at a solution I am totally stuck, here is what I could derive: Equation of tangent y=x+4 f'(x)=3ax^2+b Dont know what to do, can someone please help?