关于x的一元二次方程-x2+（2m+1）x+1-m2=0无实数根，则m的取值范围是 ______．
∵关于x的一元二次方程-x2+（2m+1）x+1-m2=0的二次项系数a=-1，一次项系数b=（2m+1），常数项c=1-m2，
∴△=（2m+1）2-4×（-1）（1-m2），即△=4m+5，
又∵原方程无实根，
∴△＜0，即4m+5＜0，
解得，m＜-
；5 4
故答案为：m＜-
．5 4
| 用方框内所给动词的适当形式填空。 | |
2. He is not a good student, because he never ______ the books to the library on time. 3. —What are you doing? —We ______ for the exam. 4. The foreigners ______ the school, are they? 5. Look! The boy ______ faster and faster. 6. The twins usually ______ milk and bread for breakfast, but Jim ______ some porridge for it. 7. The girl ______ wearing a skirt. Look! She ______ a red skirt today. 8. The old worker ______ the students around the factory now. 9. It ______ heavily now, but it ______ soon. 10. Listen! Who's at the door? Someone ______ at the door. |