二次型f(x1,x2,x3)=2x12＋5x22＋5x32＋4x1x2−8x2x3，则f的矩阵为() A: (24005−8005) B: (24005−40−45) C: (22025−40−45) D: (24045−40−45)
二次型f(x1,x2,x3)=2x12＋5x22＋5x32＋4x1x2−8x2x3，则f的矩阵为() A: (24005−8005) B: (24005−40−45) C: (22025−40−45) D: (24045−40−45)
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