解析:由{■(5"-" a>0"," @a"-" 2>0"," @a"-" 2≠1"," )┤得2

答案:C

5.下列指数式与对数式互化不正确的一组是(　　)

A.e0=1与ln 1=0

B.8^("-" 1/3)=1/2与log81/2=-1/3

C.log39=2与9^(1/2)=3

D.log77=1与71=7

解析:log39=2应转化为32=9.

答案:C

6.若loga3=m,loga5=n,则a2m+n的值是(　　)

A.15 B.75 C.45 D.225

解析:由loga3=m,得am=3,由loga5=n,得an=5,

　　∴a2m+n=(am)2·an=32×5=45.

答案:C

7.已知log3[log3(log4x) =0,则x=　　　　　.

解析:log3[log3(log4x) =0⇒log3(log4x)=1⇒log4x=3⇒x=43⇒x=64.

答案:64

8.2^(1+1/2 "·" log_2 5)的值等于　　　　　.

解析:2^(1+1/2 log_2 5)=2×2^(1/2 log_2 5)=2×(2^(log_2 5) ")" ^(1/2)=2×5^(1/2)=2√5.

答案:2√5