p(x)= 1 ag,x,-b,x, i=1 i=1 p有如下性质: (1)对一切x∈R",有7p(x)=grado(x)=Ax-b=-r(3) 证: 8眼-2,0=- i=1,2,,n wradel) =Ax-b=-r 66 1 3 n x R x x Ax b r 有如下性质: ( )对一切 ,有 ( )=grad ( )= - ( ) 1 1 , 1, 2, ..., ( ) n ij j i i j i T n a x b r i n x grad x Ax b r x x 证: 1 1 1 n n n ij i j i i i j i x a x x b x 1 ( ) 2