1. The problem statement, all variables and given/known data Find the number and position of real roots of x4+4x3-4x-13=0. 2. Relevant equations 3. The attempt at a solution I found the number of real roots using the Descarte's rule of signs. One is positive and other is negative. Now about the position of roots, i don't have any idea. Substituting the values of x and checking if f(x)=0 won't be a good idea. Also i can't factorize the given expression. I can't think of any other way for finding the roots. Is it possible to find the roots using calculus? If yes, please tell me, i would be happy to know about that. Thanks!