If a customer has a minor problem with your product or service, you might want to consider offering discount for his/her next purchase. This helps to reduce the chance of losing a customer, and minimize the cost of solving the problem.
【简答题】设向量 a =(0,2), b =(1,0),过定点A(0,-2),以 a +λ b 方向向量的直线与经过点B(0,2),以向量 b -2λ a 为方向向量的直线相交于点P,其中λ∈R, (Ⅰ)求点P的轨迹C的方程; (Ⅱ)设过E(1,0)的直线l与C交于两个不同点M、N,求 EM ? EN 的取值范围.