Question

x∈〔根号2,8〕则f(x)=(log2 x/4)·(log2 x/2)值域

已知X∈[根号2,8],试求函数f(X)=(log2 x/2)*(log2 x/4)的最大值和最小值

Answer 1

f(x)=(log2 x - 1)(log2 x - 2)
令t=log2 x t∈[1/2,3]
f(t)=t^2-3t+2
=(t-3/2)^2 -1/4
然后求出最值就OK了.