% 1 
A = [2 -1 3;0 4 5; -2 1 4]
B = [8 -3 -5; 0 1 2; 4 -7 6]
C = [0 -2 3; 1 7 4; 3 5 9];
a = 4
b = -7

aa = A+(B+C) - ( (A+B) + C )

bb = (A*B)*C - A*(B*C)

cc = (a+b)*C - a*C - b*C

dd = a*(B-C) - a*B + a*C
