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已知在數(shù)列{an}中,an=an-1+4,a3=10,求,數(shù)列{an}的通項(xiàng)公式
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你好,我手邊沒(méi)筆和紙,只能告訴你大致算法。an_1=an_2+4…依次寫(xiě)到a3=a2+4;a2=a1+4。把這些式子加起來(lái),知道a3=10,可以求出a1。
2024 12/26 19:46
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張瑞雪老師 
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2024 12/26 19:49
然后Sn-a1=Sn-1+4n,an=Sn-Sn_1=a1+4n。就出結(jié)果。大致算法就是這樣,我沒(méi)筆和紙,見(jiàn)諒。
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