A.lgM=lgM(M＞0)                                    B.lg=lgM(M＞0)

C.lgM=nlgM(M＞0)                                      D.lgM=lgM(M＞0)

若lg2=0.3010，则lg5=________，lg20=________，lg200=________，lg=________，

lg=________，lg2ⁿ=________.

A.a=4(a>0且a≠1)                                  B.log_aa²=2(a>0且a≠1)

C.2=x                                                    D.log3=1

A.log₂［(－3)(－5)］=log₂(－3)+log₂(－5)

B.lg(－10)²=2lg(－10)

C.log₂［(－3)(－5)］=log₂3+log₂5

D.log₃(－3)³=－log₃3³

A.lg(x²y)=(lgx)²+lgy+                         B.lg(x²y)=(lgx)²+lgy+2lgz

C.lg(x²y)=2lgx+lgy－2lgz                             D.lg(x²y)=2lgx+lgy+lgz

①log_ax·log_ay=log_a(x+y)；②log_ax+log_ay=log_a(x+y)；③log_a()=log_a(x－y)；④log_a(x－y)=.

其中正确的个数是

A.0                                                                 B.1

C.2                                                                 D.3

(2)设f(x)=log_ax(a＞0,且a≠1),若f(3)－f(2)=1,求f(3.75)+f(0.9)的值；

(3)已知方程lg²x+(lg2+lg3)lgx+lg2·lg3=0的两个根为x₁、x₂,求x₁x₂的值.

(2)用log_ax，log_ay，log_az表示log_a.