b)
(x11x21x12x22)∗(0110)=(x12x22x11x21)x1=(x11x21);x2=(x12x22)
c)
⎝⎛x11x21x31x12x22x32x13x23x33⎠⎞∗⎝⎛111⎠⎞=⎝⎛x11+x12+x13x21+x22+x23x31+x32+x33⎠⎞
d)(x11x21x12x22)∗(111−1)=(x11+x12x21+x22x11−x12x21−x22)