9b1b2b3的精選

問題詳情：.已知-9,a1,a2,-1四個實數成等差數列，-9,b1,b2,b3,-1五個實數成等比數列，則b2(a2-a1)=(    )A.8            B.-8            C.±8             D.7【回答】B知識點...