已知等比數列an滿足an大於0,n=1,2.且a5乘a2n-5=2的2n(n大於等於3) 已知等比數列{an}滿足an>0,n=1,2,…,且a5-a2n-5=2^2n(n>=3),且當n>=1時, log 2 a1+log 2 a3+…log 2 a2n-1= 已知等比數列{an}滿足an>0,n=1,2,且a(5)乘a(2n-5)=2^2n(n>=3),且當n>=1時, log 2 a1+log 2 a3+…+log 2 a2n-1=

已知等比數列an滿足an大於0,n=1,2.且a5乘a2n-5=2的2n(n大於等於3) 已知等比數列{an}滿足an>0,n=1,2,…,且a5-a2n-5=2^2n(n>=3),且當n>=1時, log 2 a1+log 2 a3+…log 2 a2n-1= 已知等比數列{an}滿足an>0,n=1,2,且a(5)乘a(2n-5)=2^2n(n>=3),且當n>=1時, log 2 a1+log 2 a3+…+log 2 a2n-1=

a(5)乘a(2n-5)=2^2n
利用等比數列的性質
a(5)乘a(2n-5)=a1*a(2n-1)=2^(2n)
log 2 a1+log 2 a3+…+log 2 a2n-1共n項
=log2 [a1*a3.a(2n-1)]
=(1/2)log2 [a1*a3.a(2n-1)]²;
=(1/2)log2 [a1*a(2n-1)]^n
=(1/2)log2 [2^(2n)]^n
=(1/2)*(2n²;)
=n²;