已知等比数列{an}中满足an大于0,n为正整数且a5*a2n-5=2的2n次方则n大于等于1时,loga1+loga2+...+loga2n-1A n{2n-1} B {n+1}2 C n2 D{n-1}2
问题描述：
已知等比数列{an}中满足an大于0,n为正整数且a5*a2n-5=2的2n次方则n大于等于1时,loga1+loga2+...+loga2n-1
A n{2n-1} B {n+1}2 C n2 D{n-1}2
答
貌似你漏打字了.应该是log2真数是a[1],a[2],…a[2n-1].答案是C∵a[n]是等比数列.又有a[5]*a[2n-5]=2^2n ∴a[1]*a[2n-1]=2^2n设a[n]得公比为q.∵a[1]*q^n-1=a[n],a[2n-1]=a[1]*q^2n-2,∴a[1]*a[2n-1]=(a[1]*q*n-1)&su...