问题
填空题
函数y=lnx-x2的极值点为______．
答案
函数的定义域为（0，+∞），
y′=
-2x=1 x
，1-2x2 x
令y′=0，得x=
，2 2
当0＜x＜
时，y′＞0，当x＞2 2
时，y′＜0，2 2
所以当x=
时函数取得极大值，2 2
为函数的极大值点，2 2
故答案为：
．2 2
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函数y=lnx-x2的极值点为______．
函数的定义域为（0，+∞），
y′=
-2x=1 x
，1-2x2 x
令y′=0，得x=
，2 2
当0＜x＜
时，y′＞0，当x＞2 2
时，y′＜0，2 2
所以当x=
时函数取得极大值，2 2
为函数的极大值点，2 2
故答案为：
．2 2
| 完形填空。阅读下面短文，掌握其大意，然后从各小题所给的四个选项中选出最佳选项。 | ||||
| Miss Joan was a kindergarten (幼儿园) teacher who taught in a small village school. She always worked long hours to prepare interesting 1 for her students. She also helped the other teachers, giving them many good 2 to help them teach better. She loved her students and they loved her, too. Yes, in many ways she was nearly perfect. 3 , she did have two small shortcomings (缺点). First, she would always 4 snacks in her desk. Sometimes the food attracted mice and other unwanted guests. Her the other shortcoming was that she was 5 afraid of snakes. She would not allow anyone in her class to 6 pictures of snakes or even say the word. She was even afraid when her kids were 7 about words that start with the letter S. One day these two things came 8 . A teacher 9 knew about Miss Joan's two shortcomings decided to make fun of her. He bought a toy snake in a shop. When Miss Joan wasn't in the classroom, he took away some of her snacks and put the toy snake 10 her desk instead. When Miss Joan took out the snack to eat, she saw a toy snake. She was too frightened to move, and from then on she never hide snacks in her desk. | ||||
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