已知集合,,则( )
设,且,则( )
奇函数的定义域为R,若为偶函数,且=1,则+=( )
若 =, 则的最小值是
已知ABC的内角A、B、C所对的边分别为、、,若B="2A," =1,b=,则=A.2 B.2 C. D.1
已知数列是等比数列,是其前项和,且="2," ,则=