x24x3的精選

問題詳情：當x∈[-2,1]時,不等式ax3-x2+4x+3≥0恆成立,則實數a的取值範圍是()A.[-5,-3]              B.C.[-6,-2]              D.[-4,-3]【回答】C.當x∈(0,1]時,得a≥-3-4+,令t=,則t∈[...