lg(7*2^x+8)≥log(√10) 2^x,即lg(7*2^x+8)≥log(10) [2^(2x)],7*2^x+8≥2^(2x)2^(2x)- 7*2^x-8≤0,-1≤2^x≤8,x≤3.则log(1/2)x≥log(1/2)3,设log(1/2)x=t,t≥log(1/2)3.f(x)=log(1/2)x*log[(1/2)x/4]= log(1/2)x*[...