设实对称矩阵A=
(020
21-1
0-12),
则对应的二次型f(x1,x2,x3)=xTAx为()
A.x12+2x22+4x1x2-2x2x3 B.x22+2x32+4x1x2-2x2x3 C.x12+2x32+4x1x3-2x2x3 D.x22+2x32+2x1x2-x2x3正确答案B
设实对称矩阵A=
(020
21-1
0-12),
则对应的二次型f(x1,x2,x3)=xTAx为()
A.x12+2x22+4x1x2-2x2x3 B.x22+2x32+4x1x2-2x2x3 C.x12+2x32+4x1x3-2x2x3 D.x22+2x32+2x1x2-x2x3正确答案B