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填空:(1)数列:-a,a^2,-a^,a^,…,第n个数是(2)数列:a,-a^2,a^,-a^,…,第n个数是(3)观察:1^2+1=(1-1)^2+2×1,2^2+1=(1-2)^2+2×2,3^2+1=(1-3)^2+2×3,4^2+1=(1-4)^2+2×4.规律:

题目详情
填空:(1)数列:-a,a^2,-a^,a^,…,第n个数是
(2)数列:a,-a^2,a^,-a^,…,第n个数是
(3)观察:1^2+1=(1-1)^2+2×1,2^2+1=(1-2)^2+2×2,3^2+1=(1-3)^2+2×3,4^2+1=(1-4)^2+2×4.规律:
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答案和解析
(1)数列:-a,a^2,-a^3,a^4,…,第n个数是:(-1)^n*a^n
(2)数列:a,-a^2,a^,-a^,…,第n个数是:(-1)^(n+1)*a^n
(3)观察:1^2+1=(1-1)^2+2×1,2^2+1=(1-2)^2+2×2,3^2+1=(1-3)^2+2×3,4^2+1=(1-4)^2+2×4.规律:n^2+1=(1-n)^2+2n