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设集合A={1,2,3,4,5}共有k个子集,记作Ai(i=1,2,…k),设Ai的元素之和为Si=(i=1,3,…k),则S1+S2…+Sk=?
设集合A={y/y=x²-2x+3,x∈R},B={y/y=-x²+2x+10,x∈R},求A∩B设集合A={(x,y)/y=x+1,x∈R},B={(x,y)/y=-x²+2x+3/4,x∈R},求A∩B
【1.he()carefully,buthe()nothing.Alisten,hearBlisten,heardClistened,hearDlistened,heard2.ifyoudon't()carefully,youcan't()thesound.Ahear,listenBlisten,listentoChear,hearDlisten,hear】