Question

用描述法表示集合{-1/2,2/3,-3/4,4/5，...}

Answer 1

{x|x=(-1)^n*n/(n+1),n∈N}

Answer 2

｛n︱n／n+1×（-1）n次方｝

Answer 3

{x│x=(-1)^n*n/(n+1),n∈N+}

Answer 4

{x/x=[（-1）^n]n/(n+1)