简单计算一下即可，答案如图所示
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第1个回答 2021-08-18
A11 = 3, A12 = 0, A13 = 0
A21 = 0, A22 = 4, A23 = -2
A31 = 0, A32 = -2, A33 = 4
则 f = (1/6)[3(x1)^2+4(x2)^2-4x2x3+4(x3)^2]
B =
[1/2 0 0]
[0 2/3 -1/3]
[0 -1/3 2/3]
A21 = 0, A22 = 4, A23 = -2
A31 = 0, A32 = -2, A33 = 4
则 f = (1/6)[3(x1)^2+4(x2)^2-4x2x3+4(x3)^2]
B =
[1/2 0 0]
[0 2/3 -1/3]
[0 -1/3 2/3]
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