作业帮等比数列{An}的各项均为正数,且a5a6+a4a7=18,则log3a1+log3a2+…+log3a10=A12 B10 C8 D2+log3 5
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等比数列{An}的各项均为正数,且a5a6+a4a7=18,则log3a1+log3a2+…+log3a10=A12 B10 C8 D2+log3 5
等比数列{An}的各项均为正数,且a5a6+a4a7=18,则log3a1+log3a2+…+log3a10=
A12 B10 C8 D2+log3 5
等比数列{An}的各项均为正数,且a5a6+a4a7=18,则log3a1+log3a2+…+log3a10=A12 B10 C8 D2+log3 5
a5a6=a4a7=a3a8=a2a9=a1a1不解释了撒
log3a1+log3a2+…+log3a10=log3a1a2a3…a10也不解释了撒
那不就是log3 9*5=log3 9+log3 5=D选项了嘛
解:
由于{an}为等比数列
则:a5a6=a4a7=a3a8=a2a9=a1a10
又a5a6+a4a7=18
则:
2a5a6=18
a5a6=9
则:
log3(a1)+log3(a2)+...+log3(a9)+log3(a10)
=log3[a1*a2*a3*...*a10]
=log3[(a1a10)*(a...
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解:
由于{an}为等比数列
则:a5a6=a4a7=a3a8=a2a9=a1a10
又a5a6+a4a7=18
则:
2a5a6=18
a5a6=9
则:
log3(a1)+log3(a2)+...+log3(a9)+log3(a10)
=log3[a1*a2*a3*...*a10]
=log3[(a1a10)*(a2a9)*...*(a5a6)]
=log3[9*9*...*9]
=log3[9^5]
=log3[3^10]
=10log3[3]
=10
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B
a5a6=a4a7=a3a8=a2a9=a1a1=9
log3a1+log3a2+…+log3a10=log3a1a2a3…a10=log3 9^5=log3 3^10=10
选B