f=x2+2x2+5x3+2xx2+2x1x3+6x2x3 所用变换矩阵为 1-11 C=|01-2(c-=1≠0 0011 2 1 3 2 3 2 3 2 2 2  f = x1 + 2x + 5x + 2x x + 2x x + 6x x . 2 2 2 1 = y + y 所用变换矩阵为 , ( 1 0). 0 0 1 0 1 2 1 1 1 =            − − C = C