Question

第十题，谢谢

Answer 1

数列是等比数列，则a1·a10=a2·a9=a3·a8=a4·a7=a5·a6
log2(a1)+log2(a2)+...+log2(a10)
=log2(a1·a2·...·a10)
=log2[(a1a10)·(a2a9)·(a3a8)·(a4a7)·(a5a6)]
=log2[(a5a6)⁵]
=5log2(a5a6)
=5log2(4)
=5·2
=10
选C

Answer 2

a5×a6=a1²×q^9=4
T10=log2为底 a1×a2×....×a10
=log2为底 [(a1)^10×q^(1+2+...+9)]
=log2为底 [(a1)^10×q^45]
=5log2为底 [(a1)²×q^9]
=5log2为底 4
=10
选C