若数列{an}满足下列条件,分别求其通项公式(1) a1=1 ,an+1=an+2根号an +1(2)a1=1 ,an+1=3an+2 (3)a1=1,sn=3an+1+2PS; an+1是连在一起的.
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若数列{an}满足下列条件,分别求其通项公式(1) a1=1 ,an+1=an+2根号an +1(2)a1=1 ,an+1=3an+2 (3)a1=1,sn=3an+1+2PS; an+1是连在一起的.
若数列{an}满足下列条件,分别求其通项公式
(1) a1=1 ,an+1=an+2根号an +1
(2)a1=1 ,an+1=3an+2
(3)a1=1,sn=3an+1+2
PS; an+1是连在一起的.
若数列{an}满足下列条件,分别求其通项公式(1) a1=1 ,an+1=an+2根号an +1(2)a1=1 ,an+1=3an+2 (3)a1=1,sn=3an+1+2PS; an+1是连在一起的.
(1) an+1=an+2根号an +1=(根号an +1)^2
根号an+1=根号an +1
bn=根号an=n,
an=bn^2=n^2
(2)a1=1 ,an+1=3an+2 an+1 +1=3(an +1)
bn=an +1=2*3^(n-1) an=2*3^(n-1) -1
(3)a1=1,sn=3an+1+2
s(n+1)=3an+2+2所以an+1=s(n+1)-sn=3a(n+2)-3a(n+1)
a(n+2)=4/3a(n+1) an=(4/3)^(n-1)
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(2)a1=1 ,an+1=3an+2 an+1 +1=3(an +1)
bn=an +1=2*3^(n-1) an=2*3^(n-1) -1
(3)a1=1,sn=3an+1+2
s(n+1)=3an+2+2所以an+1=s(n+1)-sn=3a(n+2)-3a(n+1)
a(n+2)=4/3a(n+1) an=(4/3)^(n-1)