已知数列{An} 满足A1=1,An=A{n-1}+2 (n大于等于2),A5等于多少
An是等差数列。A5=9
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(1)设数列{an}满足a1=1,an=(1/a(n-1))+1(n≥2),则a5=答:a5=3/5 +1=8/5.(2)a(n+1)=(an- √3)/( √3an+1),a1=0.a2=-√3, a3=-2√3/(-2)=√3, a4=0,可知数列每3项一循环, 2011=3*670+1,a2011=a1=0.(3)①an=1/(n+1),②an=[(n+1)²-1]/(n+1),③an=[(-1)^(n-1)] * 1/[n(n+1)]