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已知数列满足a1=0,an+1=an+2n,求a100已知数列满足a1=0,an+1=an+n,求a100是n不是2n

题目详情
已知数列满足a1=0,an+1=an+2n,求a100
已知数列满足a1=0,an+1=an+n,求a100是n不是2n
▼优质解答
答案和解析
a100=a99+2×99
a99=a98+2×98
.
a3=a2+2×2
a2=a1+2×1
相加,得
a100=a1+2×(1+2+.+99)
=0+2×(1+99)×99÷2
=9900