已知命题P：函数y=loga
若P∨Q是真命题，P∧Q是假命题，求实数a的取值范围． |
解∵命题P为真命题，即
函数y=loga
在定义域上单调递增；x+2 x-1
∴0＜a＜（5分）
若命题Q为真命题，
不等式（a-3）x2+（2a-6）x-5＜0对任意实数x恒成立；
当a-3=0时，不等式为-5＜0满足题意，
当a≠0时，令a-3＜0且△=（2a-6）2+20（a-3）＜0
解得-2＜a≤3（10分）
∵P∨Q是真命题且P∧Q是假命题，
∴P，Q有一个真命题一个假命题，
当p真Q假时，有
无解0＜a＜1 a≤-2或a＞3
当Q真P假时，有a≤0或a≥1 -2＜a≤3
解得-2＜a≤0或1≤a≤3．
∴a的取值范围是-2＜a≤0或1≤a≤3． （14分）
根据下面提供的对话情景，从下列7个选项中选择正确答案，使对话连贯、完整。请将答案代号写在题后的横线上，其中有两项是多余的。  Nathan: There is a festival in June in our country, it’s Father’s Day. 1 Li Fei: Yes, it’s on the fifth day of the fifth lunar(阴历)month. We call it Dragon Boat Festival Nathan: 2 Li Fei: We make and eat zongzi and hold dragon boat races. Nathan: 3 Why do you celebrate Dragon Boat Festival? Li Fei: Oh, it is a story about Qu Yuan. He lived about two thousand years ago. His job was to give advice to the emperor. But he wasn’t trusted and often got punishment. So he jumped into the Miluo River and died. Nathan: 4 Was the day that Qu Yuan died on the fifth day of the fifth lunar month in that year? Li Fei: 5 From then on , Chinese people began to eat zongzi and have dragon boat races on that day to memorize him.
小题1: 小题2: 小题3: 小题4: 小题5: |