If\ A = \\\\displaystyle\\\\left[\\\\begin{array}{ccc} \ 2 &-3 &8 \\\\cr \ 8 &4 &-8 \\\\cr \ -3 &6 &-9 \\\\cr \ 4 &-5 &-1 \\\\cr \ \\\\end{array}\\\ ight]\ B = \\\\displaystyle\\\\left[\\\\begin{array}{ccc} \ 9 &-6 &9 \\\\cr \ -6 &-8 &-9 \\\\cr \ -2 &9 &0 \\\\cr \ -9 &2 &-9 \\\\cr \ \\\\end{array}\\\ ight]\ C = \\\\displaystyle\\\\left[\\\\begin{array}{cccc} \ 5 &-5 &-3 &9 \\\\cr \ 9 &-7 &-4 &4 \\\\cr \ \\\\end{array}\\\ ight]\ \ then decide if each of the following operations is defined (answer yes or no)