求数列{an}{bn}满足a1=1,a2=r,r>0,bn=ana(n+1)且{bn}是公比为q的等比,设Cn=a (2n-1)+a2n(1)求{an}通项(2)设dn=lgC(n+1)/lgCn,求{dn}最大项与最小项的值r=2的19.2次方-1,q=1/2
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![求数列{an}{bn}满足a1=1,a2=r,r>0,bn=ana(n+1)且{bn}是公比为q的等比,设Cn=a (2n-1)+a2n(1)求{an}通项(2)设dn=lgC(n+1)/lgCn,求{dn}最大项与最小项的值r=2的19.2次方-1,q=1/2](/uploads/image/z/4551476-68-6.jpg?t=%E6%B1%82%E6%95%B0%E5%88%97%7Ban%7D%7Bbn%7D%E6%BB%A1%E8%B6%B3a1%3D1%2Ca2%3Dr%2Cr%3E0%2Cbn%3Dana%28n%2B1%29%E4%B8%94%7Bbn%7D%E6%98%AF%E5%85%AC%E6%AF%94%E4%B8%BAq%E7%9A%84%E7%AD%89%E6%AF%94%2C%E8%AE%BECn%3Da+%282n-1%29%2Ba2n%281%29%E6%B1%82%7Ban%7D%E9%80%9A%E9%A1%B9%282%29%E8%AE%BEdn%3DlgC%28n%2B1%29%2FlgCn%2C%E6%B1%82%7Bdn%7D%E6%9C%80%E5%A4%A7%E9%A1%B9%E4%B8%8E%E6%9C%80%E5%B0%8F%E9%A1%B9%E7%9A%84%E5%80%BCr%3D2%E7%9A%8419.2%E6%AC%A1%E6%96%B9-1%2Cq%3D1%2F2)
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求数列{an}{bn}满足a1=1,a2=r,r>0,bn=ana(n+1)且{bn}是公比为q的等比,设Cn=a (2n-1)+a2n(1)求{an}通项(2)设dn=lgC(n+1)/lgCn,求{dn}最大项与最小项的值r=2的19.2次方-1,q=1/2
求数列{an}{bn}满足a1=1,a2=r,r>0,bn=ana(n+1)且{bn}是公比为q的等比,设Cn=a (2n-1)+a2n
(1)求{an}通项
(2)设dn=lgC(n+1)/lgCn,求{dn}最大项与最小项的值
r=2的19.2次方-1,q=1/2
求数列{an}{bn}满足a1=1,a2=r,r>0,bn=ana(n+1)且{bn}是公比为q的等比,设Cn=a (2n-1)+a2n(1)求{an}通项(2)设dn=lgC(n+1)/lgCn,求{dn}最大项与最小项的值r=2的19.2次方-1,q=1/2
b1 = a1a2 = r,故bn = r*q^(n-1)
又b(n+1)/bn = a(n+1)*a(n+2)/(an*a(n+1)) = a(n+2)/an、b(n+1)/bn = q
可得当n为奇数时an = a1*q^((n+1)/2 - 1) = q^((n-1)/2)
当n为偶数时an = a2*q^(n/2 - 1) = r*q^(n/2 - 1)
cn = a(2n-1)+a2n = q^(n-1) + r*q^(n-1) = (1+r)*q^(n-1)
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