(4,2,1 (1 (1
x,1,2 * -2 =r * -2 (设特征值为r)
3,y,-1) 3) 3)
则可得
(3 (1
x+4 = r -2 所以3=r,x+4=-2r,-2y=3r
-2y) 3)
可解得：x=-10,y=-9/2