2.a1=1,an+1=3an+(2^n),则an=?3.
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2.a1=1,an+1=3an+(2^n),则an=?3.
2.a1=1,an+1=3an+(2^n),则an=?3.
2.a1=1,an+1=3an+(2^n),则an=?3.
(2)a(n+1)=3an+2^n
an+1 + 2^(n+1) = 3*(an+2^n)
令bn=an+2^n
则bn+1/bn=3
即bn是以3为公比的等比数列
bn=b1*3^(n-1)=3^n
即an+2^n=3^n
an=3^n-2^n
(3)an=2a(n-1)+1
an+1=2a(n-1)+2=2(a(n-1)+1)
令bn=an+1
所以bn是公比为2的等比数列
所以bn=(-3+1)*2^(n-1)=-2^n
an=-2^n-1
[a(n+1)–2⌒n]÷3
数列{an},a1=1,an+1=2an-n^2+3n,求{an}.
2.a1=1,an+1=3an+(2^n),则an=?3.
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