公式:1/[(2n-1)(2n+1)]=(1/2)[1/(2n-1)-1/(2n+1)]
a1+a2+a3+a4+……+a100
=(1/2)(1-1/3+1/3-1/5+……+1/199-1/201)
=(1/2)(1-1/201)
=100/201
公式:1/[(2n-1)(2n+1)]=(1/2)[1/(2n-1)-1/(2n+1)]
a1+a2+a3+a4+……+a100
=(1/2)(1-1/3+1/3-1/5+……+1/199-1/201)
=(1/2)(1-1/201)
=100/201