【简答题】Marksuggests that they _____.A. (a) eat their picnic while travelling along the river B. (b) move over to the bank and stop for a while C. (c) eat their picnic in about ten minutes D. (d) move over to...
【简答题】椭圆C的中心在坐标原点O,焦点在y轴上,离心率为 2 2 ,以短轴的一个端点与两焦点为顶点的三角形的面积为 1 2 . (1)求椭圆C的方程; (2)若过点P(0,m)存在直线l与椭圆C交于相异两点A,B,满足: AP =λ PB 且 OA +λ OB =4 OP ,求常数λ的值和实数m的取值范围.