设二次型f的矩阵A=【2 0 -1,0 1 0,-1 0 1】则f(x1,x2,x3)等于?
问题描述:
设二次型f的矩阵A=【2 0 -1,0 1 0,-1 0 1】则f(x1,x2,x3)等于?
答
2(x1)^2-2(x1*x3)+(x2)^2+(x3)^2
设二次型f的矩阵A=【2 0 -1,0 1 0,-1 0 1】则f(x1,x2,x3)等于?
2(x1)^2-2(x1*x3)+(x2)^2+(x3)^2