%#2
A=[0 0 -3; 0 5 4; 2 -8 1]
%#6
B=[ -4 -3 0; 0 -1 4 ; 1 0 3 ; 5 4 6]
%#8
 C=[ 1 -3 3 -2; -3 7 -1 2; 0 1 -4 3]
 C*[9 ;4;1;0]
 %#12 #16, #18