设{an}是由正数组成的等比数列,且a5a6=81,log3a1+log3a2+…+log3a10的值是( )A.5B.10C.20D.2或4
题型:单选题难度:简单来源:不详
设{an}是由正数组成的等比数列,且a5a6=81,log3a1+log3a2+…+log3a10的值是( ) |
答案
∵{an}是由正数组成的等比数列,且a5a6=81, ∴a1a10=a2a9=a3a8=a4a7=a5a6=81, ∴log3a1+log3a2+…+log3a10 =log3(a1?a2?…?a10) =log3(a5a6)5 =5log3(a5a6) =5log381 =5?4=20 故选C. |
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