数列an中a1=1,a(n+1)=2an+3(n≥1),通项an=?,n、n+1为下标
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![数列an中a1=1,a(n+1)=2an+3(n≥1),通项an=?,n、n+1为下标](/uploads/image/z/8664902-62-2.jpg?t=%E6%95%B0%E5%88%97an%E4%B8%ADa1%3D1%2Ca%EF%BC%88n%2B1%EF%BC%89%3D2an%2B3%28n%E2%89%A51%29%2C%E9%80%9A%E9%A1%B9an%3D%3F%2Cn%E3%80%81n%2B1%E4%B8%BA%E4%B8%8B%E6%A0%87)
数列an中a1=1,a(n+1)=2an+3(n≥1),通项an=?,n、n+1为下标
数列an中a1=1,a(n+1)=2an+3(n≥1),通项an=?,n、n+1为下标
数列an中a1=1,a(n+1)=2an+3(n≥1),通项an=?,n、n+1为下标
a(n+1)+3=2an+6
a(n+1)+3=2(an+3)
数列{an+3}为等比数列
an+3=(a1+3)*2^(n-1)
an+3=2^(n+1)
an=2^(n+1)-3
等式两边都加三,a(n)加3是等比数列
a(n+1)+1=2(an+1)
数列{an+1}是首项为2,公比为2的等比数列
an+1=2^n
an=2^n-1