Demonstrati relatiile:a vector +b vector +c vector +d vector= (a vector + b vector)+(c vector + d vector); a vector - b vector= -(b vector - a vector )
prima relatie e demonstrata deoarece adunarea vectorilor e comutativa ascociativa etc, (a vector - b vector)=-b vector +a vector=-(b vector-a vector) regula semnelor de la matematica
