根值审敛法怎么用 用比值审敛法或根值审敛法判别n/2n+1^n+1的敛散性
1.用比值审敛法或根值审敛法判别（n/(2n+1))^(n+1)的敛散性a(n+1)=[n/(2n+1)]^(n+1)。a(n+1)=[1/(2+1/n)]^(n+1)→1/2^(n+1)→0。数列{a(n)}收敛。【1】比值判定。a(n+1)/a(n)=[n/(2n+1)]^(n+1)/[(n-1)/(2n-1)]^n=[n/(2...
1.用比值审敛法或根值审敛法判别（n/(2n+1))^(n+1)的敛散性a(n+1)=[n/(2n+1)]^(n+1)。a(n+1)=[1/(2+1/n)]^(n+1)→1/2^(n+1)→0。数列{a(n)}收敛。【1】比值判定。a(n+1)/a(n)=[n/(2n+1)]^(n+1)/[(n-1)/(2n-1)]^n=[n/(2...