3.What does the woman think about the new DVD player?
A.She has no idea about it.
B.It’s no better than the old one.
C.It's better than the old one.
2.What can we learn from the conversation?
A.There’s a cat in the corner.
B.Kate is too old to move.
C.Kate doesn’t put things in order.
1.How much will the woman pay for the toy Cars?
A.40 yuan B.34 yuan C.17 yuan
已知函数.
(1) 当a=-3时,求函数f(x)的极值;
(2) 若函数f(x)的图象与x轴有三个不同的交点,求a的取值范围。
22、(本小题满分14分)
(2)椭圆C上任一动点M关于直线y=2x的对称点为M1(x1,y1),求3x1-4y1的取值范围。
已知F1,F2是椭圆C: (a>b>0)的左、右焦点,点P在椭圆上,线段PF2与y轴的交点M满足。
(1)求椭圆C的方程。
21、(本小题满分12分)
(II) 若bn=,sn=b1+b2+┉+bn,对任意正整数n,sn+(n+m)an+1<0恒成立,试求m的取值范围。