How do you know the multiplicity is 2?
f(x)= x^4 - x^3 - 20x^2
Find all real zeros and determine the multiplicity of each.
i did my factors and got 5,4,1,20,10,2
so i did synthetic with 5 and it was a factor. then I did synthetic with -4 and it was a factor. then x= 0 another zero. And then if I do synthetic again -4 comes out again. My question is how can I know that -4 has a multiplicity of 2 without having to do synthetic to find out so.