1*5/1+5*9/1+9*13/1+13*17/1+.......45*49/1
来源:百度知道 编辑:UC知道 时间:2024/06/18 17:52:35
上面是分子吧,应该是这样写:
1/1*5+1/5*9+...+1/45*49
=1/4[1-1/5]+1/4[1/5-1/9]+...+1/4[1/45-1/49]
=1/4[1-1/5+1/5-1/9+...+1/45-1/49]
=1/4*[1-1/49]
=1/4*48/49
=12/49
1/[n*(n+4)]=[1/n-1/(n+4)]/4
原式=[(1-1/5)+(1/5-1/9)+……+(1/45-1/49)]/4
=(1-1/49)/4
=12/49
1/(3*5)+1/(5*7)+1/(7*9)+----+1/(1997*1999)
1/5*9+1/9*13+1/13*17+...+1/101*105
1/3*1+1/5*3+1/7*5+1/9*7+.....1/2007*2005
1/6<( )<1/5 5/9>( )>4/9
1-1/3-1/5+1/3-1/5-1/7+1/5-1/7-1/9……+1/2003-1/2005-1/2007
1/5+1/7+1/9+.....+1/1999=
1/3+1/5+1/7+1/9+1/11..+1/99
1/3+1/5+1/7+1/9+1/11+ ...............+1/2001=?
1/3+1/5+1/7+1/9+1/11+...1/99=?
1/9,1/3,5/9,7/9,( )