1-1/21/3(1-1/2+1/3
1-1/2+1/3-1/4+。。。+1/99-1/100=1+1/3+1/5+。。。+1/99-1/2-1/4-1/6-。。。-1/100
=(1+1/2+1/3+1/4+。。。+1/99+1/100)-2(1/2+1/4+1/6+。 。。+1/100)
=(1+1/2+1/3+1/4+。。。+1/99+1/100)-(1+1/2+1/3+1/4+。。。+1/50)
=1/51+1/52+1/53+。。。+1/99+1/100
原式=(1/51+1/52+1/53+。 。。+1/99+1/100)/[1/(1+101)+1/(2+102)+。。。+1/(50+150)
=(1/51=1...全部
1-1/2+1/3-1/4+。。。+1/99-1/100=1+1/3+1/5+。。。+1/99-1/2-1/4-1/6-。。。-1/100
=(1+1/2+1/3+1/4+。。。+1/99+1/100)-2(1/2+1/4+1/6+。
。。+1/100)
=(1+1/2+1/3+1/4+。。。+1/99+1/100)-(1+1/2+1/3+1/4+。。。+1/50)
=1/51+1/52+1/53+。。。+1/99+1/100
原式=(1/51+1/52+1/53+。
。。+1/99+1/100)/[1/(1+101)+1/(2+102)+。。。+1/(50+150)
=(1/51=1/52+1/53+。。。+1/99+1/100)/[1/2(1/51+1/52+1/53+。
。。+1/100)
=2。收起
