【導(dǎo)讀】2.已知A,B均為集合U={1,3,5,7,9}的子集,且A∩B={3},A∩(?UB)={9},則A=(). B.23C.25D.29. 上是減函數(shù),則a的取值范圍是。xmxm的兩個(gè)實(shí)數(shù)根互為倒數(shù),則m=_____.。)(xf為奇函數(shù),當(dāng)0?17.已知全集U={|4}xx??的最大值為M,最小值為m,求M-m的值.時(shí),求函數(shù)()fx在3[,2]2?,且滿足條件:①()()()fxyfxfy??