u=(x1,...,xn), v=(y1,...,yn), w=(z1,...,zn)u*(v+w) = (x1,...,xn)*(y1+z1,...,yn+zn) = x1(y1+z1)+...+xn(yn+zn)= x1y1+...+xnyn + x1z1+...+xnzn=u*v + u*w
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