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数列1\/2x4 1\/4x6 1\/6x8 ……1\/2n(2n+2 )……前n项和为
14 2014-10-05 1\/2x4+1\/4x8+1\/6x8+…+1\/2012x201... 10 2011-02-09 1\/2+1\/4+1\/6+1\/8+...+1\/2n=? 15 2008-12-24 1\/2x4+1\/4x6+1\/6x8+……+1\/48x50怎样... 25 2012-12-19 数列1\/2x4+1\/4x6+1\/6x8+1\/8x10+... 3 2014-10-20 数列1\/1^2+2,1\/2^2+4,1\/...
若1\/2x4 + 1\/4x6 + 1\/6x8 + 1\/2n(2n+2) =1001\/4008,求n的值. x是乘 ...
你的题目不完整,应该是1\/(2*4) + 1\/(4*6) + 1\/(6*8) + .+1\/2n(2n+2) =1001\/4008 提出一个1\/2 得0.5=1001\/4008 括号里面化简得=1\/2[1\/2-1\/(2n+2)]=n\/2(2n+2)=1001\/4008 解得n=1001
若1\/2x4+1\/4x6+1\/6x8+…+1\/2n(2n+2)=1001\/4008,求n的值
1\/n(n+k)=(1\/k)(1\/n-1\/n+k)1\/2x4+1\/4x6+1\/6x8+…+1\/2n(2n+2)=1001\/4008 (1\/2)(1\/2-1\/4+1\/4-1\/6+……+1\/2n-1\/2n+2)=1001\/4008 1\/2-1\/2n+2=1001\/2004 1\/2n+2=1\/2004 n=1001
这题怎么做
1\/2x4+1\/4x6+1\/6x8+……+1\/2006x2008 =(1\/1x2+1\/2x3+1\/3x4+……+1\/1003x1004)×1\/4 =1003\/1004 ×1\/4。=1003\/4016。主要优势：分数除法计算法则：甲数除以乙数（0除外），等于甲数乘乙数的倒数。当除数小于1，商大于被除数；当除数等于1，商等于被除数；当除数大于1，商小于被...
1\/2x6+1\/4x6+...+2n(2n+2)=1\/2(1\/2-1\/2014)
题目错了吧，按照你这个规律应该是1\/2x4+1\/4x6+...+2n（2n+2）=1\/2（1\/2-1\/2014）解：1\/2x4+1\/4x6+...+2n（2n+2）=1\/2x(1\/2-1\/4)+1\/2x(1\/4-1\/6)+……+1\/2x[1\/(2n)-1\/(2n+2)]=1\/2x(1\/2-1\/4+1\/4-1\/6+……+1\/(2n)-1\/(2n+2)]=1\/2x(1\/2-1\/(...
1\/2x4十1\/3x5+1\/4x6...十1\/32x34?
………1\/(30*32)=(1\/30-1\/32)\/2，1\/(31*33)=(1\/31-1\/33)\/2，1\/(32*34)=(1\/32-1\/34)\/2，原式= (1\/2-1\/4)\/2+ (1\/3-1\/5)\/2 +(1\/4-1\/6)\/2+ (1\/5-1\/7)\/2+………+ (1\/30-1\/32)\/2+ (1\/32-1\/34)\/2+ (1\/32-1\/34)\/2 = 1\/2+ 1\/3-1\/33...
1\/2x4+1\/4x6+1\/6x8+...+1\/198x200 求解题过程及答案
1\/（2x4）+1\/（4x6）+1\/（6x8）+...+1\/（198x200）=1\/2*(1\/2-1\/4+1\/4-1\/6+...+1\/198-1\/200)=1\/2*(99\/200)=99\/400
数列:求Sn=1\/2x3+1\/4x6+~1\/2n(2n+2)?帮忙求解!
Sn=1\/2x4+1\/4x6+...+1\/2n(2n+2)= [ (4-2)\/2x4+(6-4)\/4x6+...+(2n+2-2n)\/2n(2n+2) ] \/2 =[ 1\/2 -1\/4 + 1\/4 -1\/6 +... + 1\/2n - 1\/(2n+2) ] \/2 = [ (n+1-1)\/2(n+1) ] \/2 =n\/ 4(n+1)
1\/2x4+1\/4x6+1\/6x8+...+1\/2006x2008
1\/2X4+1\/4X6+1\/6X8+...+1\/2006X2008＝1\/2（1\/2-1\/4+1\/4-1\/8+1\/8-1\/16+...+1\/2006-2008）＝1\/2（1\/2-1\/2008）＝1003\/（1004*4）
1\/2X4+1\/4X6+1\/6X8+...+1\/198X200要过程加答案(或者直接答案)
1\/2×4+1\/4×6+1\/6×8+...+1\/198×200 =(1\/2)(1\/2-1\/4+1\/4-1\/6+1\/6-1\/8+...+1\/198-1\/200)=(1\/2)(1\/2-1\/200)=(1\/2)(99\/200)=99\/400
