已知f(x+1)=
,f(1)=1(x∈N*),猜想f(x)的表达式为( )
(A)f(x)=
(B)f(x)=
(C)f(x)=
(D)f(x)=
知{an}是首项为-2的等比数列,Sn是其前n项和,且S3,S2,S4成等差数列,
(1)求数列{an}的通项公式.
(2)若bn=log2|an|,求数列{
}的前n项和Tn.
已知数列{an}的首项为a1=1,其前n项和为Sn,且对任意正整数n有n,an,Sn成等差数列.
(1)求证:数列{Sn+n+2}成等比数列.
(2)求数列{an}的通项公式.
已知各项都不相等的等差数列{an}的前6项和为60,且a6为a1和a21的等比中项.
(1)求数列{an}的通项公式.
(2)若数列{bn}满足bn+1-bn=an(n∈N*),且b1=3,求数列{
}的前n项和Tn.
设{an}是等差数列,{bn}是各项都为正数的等比数列,且a1=b1=1,a3+b5=21,a5+b3=13.
(1)求{an},{bn}的通项公式.
(2)求数列{
}的前n项和Sn.
等差数列{an}中,2a1+3a2=11,2a3=a2+a6-4,其前n项和为Sn.
(1)求数列{an}的通项公式.
(2)设数列{bn}满足bn=
,其前n项和为Tn,求证:Tn<
(n∈N*).
