数学,对数函数问题

2025-06-22 19:01:47
推荐回答(3个)
回答1:

f(log下2上3)=f(x+1)=f(log2(3)+1)
= f(log2(3)+log2(2))
=f(log2(6))
显然log2(6)小于4
所以f(log2(6))=f(log2(6)+1)=f(log2(6)+log2(2))=f(log2(12))
显然log2(12)小于4=log2(16)
所以f(log2(12))=f(log2(12)+1)=f(log2(12)+log2(2))=f(log2(24))
此时,log2(24)大于4了
则f(log2(24))=(1/2)^log2(24)=[2^-1]log2(24)=[2^log2(24)]^-1=24^-1=1/24

回答2:

当01则01因为当0
当a>1时,f(x)=log a (a^x-1)>1则a^x-1>a
a^x>a+1
因为当a>1时,a^x是增函数。所以x>log(a)(a+1)

回答3:

log2(3)<4
f(log2(3))
=f(log2(3)+1)
=f(log2(3)+log2(2))
=f(log2(6))
=f(log2(6)+1)
=f(log2(12))
=f(log2(12)+1)
=f(log2(24))
=(1/2)^log2(24)=1/(2^log2(24))=1/24