(61)令C则 CAC-=(% 1)(2 )(8 1)-(5 ca)再令C,-(Fg-a)，贝则-G'αGaC'(C'AC)C,-(Ea 9)(EGn-1a.010?am-a'GGα,中S5.4正定二次型区区§5. 4 正定二次型 则 1 1 1 2 1 1 2 0 ( ) 1 0 1 n n n nn E E G E G C C AC C G G a     − − −        −    =       −         1 0 0 n nn E a GG   −   =   −     令 1 ( ) 0 , 0 1 G C = 再令 1 2 , 0 1 C   E G n− −  =     则 ( ) ( ) 1 1 1 1 0 0 0 1 0 1 1 n nn G G A E G C AC G a     −        = =          