问题
选择题
已知集合M={y|y=2x，x＞0}，N={y|y=
|
答案
M={y|y=2x，x＞0}={y|y＞1}，
当x趋向于负无穷大时，2x-x3趋向于正无穷大，
又需2x-x3≥0，所以N={y|y≥0}
所以M∩N={y|y＞1}
故选C
搜题请搜索小程序“爱下问搜题”
已知集合M={y|y=2x，x＞0}，N={y|y=
|
M={y|y=2x，x＞0}={y|y＞1}，
当x趋向于负无穷大时，2x-x3趋向于正无穷大，
又需2x-x3≥0，所以N={y|y≥0}
所以M∩N={y|y＞1}
故选C
| 阅读理解。 | |||
| |||
| 1. If you want to go to Betty and Jack's party, you can call _______. | |||
| A. 342-1525 B. 342-7391 C. 342-2691 D. 342-7350 | |||
| 2. Mike Green has to sell his washing machine because _______. | |||
| A. he wants to buy a new one B. he will go to another country C. he wants to buy a new house D. There's something wrong with it | |||
| 3. Smith's Book Club is open _______ a day. | |||
| A. 8 hours B. 10 hours C. 12 hours D. 20 hours | |||
| 4. You can use the e-mail mikegreen@hotmail. com if you want to _______. | |||
| A. read some books B. go to a family party C. drink some good coffee D. buy a washing machine |