ab=(2,-3,1)(1,-1,3)=2+3+3=8,ac=(2,-3,1)(1,-2,0)=2+6=8所以 （ab)c-(ac)b=8(1,-2,0) - 8(1,-1,3)=(8,-16,0) - (8,-8,24)=(0,-8,-24)= -8 j - 24 k
