设等差数列 { a n } 的前 n 项和为 S n , S m - 1 = - 2 , S m = 0 , S m + 1 = 3 ,则 m = ( )
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
等差数列中有两项和,满足、,则该数列前mk项之和是
Ahyperbola(双曲线)wjthvertices(顶点)(-2,5)and(-2,-3),has an asynptote(渐近线)that passes the point(2.5) Then an equarionk of the hyperbola is
函数y=的最小值是