1. The problem statement, all variables and given/known data I just want to know how get from ##4x^3+3x^2-6x-5=0 ## to ##(x+1)^2(4x-5)=0##. What's the trick when dealing with these nasty polynomials? I got the answer by taking another approach (solving a root equation) but I noted this is also a way to go, but I can't figure out the method 2. Relevant equations - 3. The attempt at a solution Well I can't seem to get anywhere. The assignement is solved and correct, but I would like to learn how to make the factoring that out! =) Edit: corrected accidental + instead of - in the last factor. Edit 2: bad reception on smartphone didn't save the first correction. Now it should be fine.