1\(19*21)+1\(21*23)+1\(23*25)+...+1\(97*99)
来源:百度知道 编辑:UC知道 时间:2024/05/31 00:18:28
简便,
1\(19*21)+1\(21*23)+1\(23*25)+...+1\(97*99)
=1/2[(1/19-1/21)+(1/21-1/23)+...+(1/97-1/99)]
=1/2(1/19-1/99)
=40/1881
1\(19*21)+1\(21*23)+1\(23*25)+...+1\(97*99)
=1/2(1/19-1/21)+1/2(1/21-1/23)+...+1/2(1/97-1/99)
=1/2(1/19-1/21+1/21-1/23+...+1/97-1/99)
=1/2(1/19-1/99)
=40/19*99
原式=1/2(1/19-1/21+...-1/99)=1/2(1/19-1/99)我手机上的没草稿纸 麻烦你自己通下分嘛
1/1*3+1/3*5+1/5*7+......+1/17*19+1/19*21
(1+19/92)+(1+19/92 ×2)+(1+19/92 ×3)+…+(1+19/92 ×14)+(1+19/92 ×15)
(1+19/92)+(1+19/92 ×2)+(1+19/92 ×3)+…+(1+19/92 ×10)+(1+19/92 ×11)
奥数题: 1\3+1\6+1\10+1\15+1\21+1\28+1\36+1\45+1\55+1\66+1\78+1\91+1\105+1\120 请尽快帮忙,谢谢
计算:19×21/1+21×23/1+23×25/1……+97×99/1
计算:|1/21-1/20|+|1/22-1/21|+|1/23-1/22|+...+|1/2004-1\2003|
1*3+2*4+3*5......19*21=?
1-2+3-4+5-6~~+19-20+21
1/(1*3)+1/(3*5)+1/(5*7)+……+1/(19*21)=?
1/1×3+1/3×5+1/5×7+…1/17×19+1/19×21这道题如何简便运算?