I hope you speak english, because although i understood your question I don't know enough spanish to respond in it. You multiply polynomials by multiplying each part of one polynomial by all the other parts of the others, and then adding it all. For example: (ax+b) * (x+c) = (ax*x)+(ax*c)+(b*x)+(b*c) = 
Comprehende?
Comprehende?
