2003121087
幼苗
共回答了17个问题采纳率:88.2% 举报
an+a(n+1)=4n+1
a(n+1)+x*(n+1)+y=(-1)(an+x*n+y)
an+a(n+1)=-2x*n-x-2y
x=-2,y=1/2
a(n+1)-2(n+1)+1/2=(-1)(an-2n+1/2)
an-2n+1/2=(-1)(a(n-1)-2(n-1)+1/2)
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a2-2*2+1/2=(-1)(a1-2*1+1/2)
an-2n+1/2=(-1)^(n-1)*(-1/2)
an-2n+1/2=(-1)^n/2
an=2n+(1/2)*((-1)^n-1)
1年前
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