A.40+16+1=57
B.40+2×(16+1)=74
C.40×16+1=640
D.40×2×16×1=1280
A.ai1Ai1+ai2Ai2+…+ainAin=0
B.ai1Ai1+ai2Ai2+…+ainAin=D
C.aijAij+a2jA2j+…+anjAnj=D
D.a11A21+a12A22+…+ainA2n=0
A.8000×2.45%+8000
B.(8000×2.45%+8000)×5
C.8000×2.45%×5+8000
D.8000×2.45%×5
A.2
B.3
C.4
D.5