... ( ) 1 2 1 22 t t t t= + + 0,25 ( )2 2 2 2 2 4 4 2 1 2 3 4 1 2 3 44 2 3 4 11 x x x x x x x x m m m m+ + + + = + + + = + + . 0,25 2 2 2 2 4 2 4 2 1 2 3 4 1 2 3 4 11 4 11 11 4 ... ( )2 1 22 2 0t t m+ = + > vi mi m . 0,25 Do ú phng trỡnh (1) cú 4 nghim : 1 t, 1 t+, 2t,2t+ . ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )2 2 2 22 2 2 2 1 2 3 4 1 2 3 4 1 1 2 2 1 1 2 2x ... 0,25 Gii ra: 1 5 ; 1 5x x= = + . 0,25 Trng hp ny h cú hai nghim: ( )( ); 1 5 ;1 5x y = ; ( )( ); 1 5 ;1 5x y = + + 0,25 B.2 ( )4 2 2 42 2 3 0x m x m + + + = (1) (2) t :2t...