初中数学万题选(初二适用)·代数.pdf

5 2 1 4 3 3 m n + 2 1 4 2 1 4 1 4 8 1 4 2 4 2 3 3 3 3 2 2 m n m n m n m mn n + = + = + - + ( ) ( )( ) 3 7 6 3 7 3 2 3 7 3 49 36 49 36 2 2 2 2 x x x x x x - - = - - = - + - - = - - = + - = + - 3 7 6 11 6 3 2 3 3 3 2 3 2 2 x x x x x ( ) ( )( ) a b a b ab m + = - = - = 3 13 1 7 37 2 3 ( ) ( ) ( ) x y x y - - = - = 3 1 0 2 0 x y x y x y x y x y x y x y x y - = + = - = - + = - - = + = - = - + = - 3 1 5 3 1 5 3 5 1 3 5 1 x y x y x y x y = = = - = - = = - = - = 4 1 4 1 2 1 2 1