【简答题】Lisa never had the chance to know her father. He and her mother divorced when she was just a young child. Even though he didn’t move far, he never came to visit his children. Lisa often wondered about...
【单选题】Many young couples do not take marriage______and they get married and divorced easily.
【单选题】下列各式中: 2 x +y=1 ;3x-2y;5xy=1; x 2 +y=1 ,其中不是二元一次方程的有( )
【简答题】设x 1 ,x 2 是一元二次方程 3 x 2 +6x- 9 2 =0 的两实数根,不解方程,求下列各式的值. (1)x 1 2 -x 2 +x 1 -x 2 2 (2)|x 1 -x 2 |