已知全集,集合,则C=( )
复数= AB C D
定义,若,则()
Suppose the least distance fron poinrs of the xurve(曲线)to the y-axis is then the velue of a is
设为椭圆上一点,且,,其中为椭圆的两个焦点,则椭圆的离心率e的值等于
当x.yi满足条件时,变量U=的取值范围是