y=[(n+1)x-1](nx-1)=0
x=1/(n+1),x=1/n
n是自然数
1/n>1/(n+1)
所以原式=(1-1/2)+(1/2-1/3)+(1/3-1/4)+……+(1/1999-1/2000)
=1-1/2000
=1999/2000
y=[(n+1)x-1](nx-1)=0
x=1/(n+1),x=1/n
n是自然数
1/n>1/(n+1)
所以原式=(1-1/2)+(1/2-1/3)+(1/3-1/4)+……+(1/1999-1/2000)
=1-1/2000
=1999/2000