题目

已知a=log32,那么log38-2log36用a表示是 A.a-2                                                            B.5a-2C.3a-(1+a)2                                                 D.3a-a2-1 答案:解析:由log38-2log36=3log32-2(log32+log33)=3a-2(a+1)=a-2.答案:A
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