设,求y的极值与极值点.
参考答案:
则 y’=(x-1)ex.
令 y’=0,得唯一驻点x=1.
当x<1时,y’<0;x>1时,y’>0.
因此点x=1为y的极小值点.极小值为
在一国国际收支项目中,国际工商企业一般情况下最关注的项目是()
A.经常项目
B.资本与金融项目
C.官方储备项目
D.错误与遗漏项目
用所给动词的适当形式填空。
1. She's a cabin steward for Air China and she ______ (fly) all over the world.
2. My grandparents always eat Chinese food, they ______ never ______ (have) a west food.
3. How many English words ______ you ______ (learn)?
4. I______ never______ (speak) to a foreigner.
5. —______Tom______ (return) the library book? —Yes, he has.
—When ______he______ (return) it? —Half an hour ago.