设f(x)=1/(1+2^lgx)+1/(1+4^lg4)+1/(1+8^lgx),则f(x)+f(1/x)=?答案是3不会写.
问题描述:
设f(x)=1/(1+2^lgx)+1/(1+4^lg4)+1/(1+8^lgx),则f(x)+f(1/x)=?
答案是3
不会写.
答
f(x)= 1/(1+2^lgx) + ...;f(1/x)= 1/(1+2^lg(1/x)) + ...= 1/(1+2^(-lgx))+ ...f(x)+f(1/x) = 1/(1+2^lgx) + 1/(1+2^(-lgx)) + ...= {1+2^lgx+1+2^(-lgx)}/{1+2^lgx+2^(-lgx)+2^lgx*2^(-lgx)+ ...= (1+ 1 2^(lgx-lgx...