1/2x4+1/3x5+1/4x6+1/5x7+...+1/97x99=?RT

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1/2x4+1/3x5+1/4x6+1/5x7+...+1/97x99=?RT

1/2x4+1/3x5+1/4x6+1/5x7+...+1/97x99=?RT
1/2x4+1/3x5+1/4x6+1/5x7+...+1/97x99=?
RT

1/2x4+1/3x5+1/4x6+1/5x7+...+1/97x99=?RT
应该是1/（2*4）形式吧
1/（2*4）=1/2*（1/2-1/4）,1/（3*5）=1/2*（1/3-1/5）……
所有项都按此拆分
则原式=1/2*（1/2+1/3-1/98-1/99）=355/4851

应该是1/（2*4）形式吧
1/（2*4）=1/2*（1/2-1/4），1/（3*5）=1/2*（1/3-1/5）……
所有项都按此拆分
则原式=1/2*（1/2+1/3-1/98-1/99）=355/4851

=1/2[1/2-1/4+1/3-1/5+1/4-1/6+1/5-1/7+……1/96-1/98+1/97-1/99]
=1/2[1/2+1/3-1/98-1/99]
=12/49+16/99

裂项求和呀
1/n(n+2)=1/2[1/n-1/(n+2)]
所以1/(2x4)=1/2(1/2-1/4)
1/(3x5)=1/2(1/3-1/5)
……
所以原式=1/2[(1/2-1/4)+(1/3-1/5)+(1/4-1/6)+(1/5-1/6)+…+(1/96-1/98)+(1/97-1/99)]
=1/2[]1/2+1/3-1/98-1/99]
=1/2(48/98+32/99)
=12/49+16/99

1/1x3+1/2x4+1/3x5+1/4x6+...+1/100x102=? 1/1x3+1/2x4+1/3x5+1/4x6+...+1/10x12 1x3+2x4+3x5+4x6..+99x101=? 1x2+2x3+3x4+4x5+5x6---+99x100=? 1x2+2x3+3x4+4x5+5x6+.+99x100 巧算：1x2+2x3+3x4+4x5+5x6+6x7...+8x9 x1-x2+x3=1x2-x3+x4=21若x1,x2,x3,x4,x5满足方程组 x3-x4+x5=3x4-x5+x1=4x5-x1+x2=5求x2 x3 x4的值2已知 x1+x4+x6+x7=39 x2+x4+x5+x7=49 x3+x5+x6+x7=41 x4+x7=13 x5+x7=14 x6+x7=9 x1+x2+x3+x4+x5+x6+x7=9求x7的值若x1,x2,x3,x4,x5满足方程组 x1-x 1/1x3+1/2x4+1/3x5+1/4x6+1/5x7+1/6x8 1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+......1/2008x2009 1/1x2+2/1x3+3/1x4+4/1x5+5/1x6+6/1x7= 1/2x4+1/3x5+1/4x6+1/5x7+.1/8x10+1/9x11 1/2x4+1/3x5+1/4x6+1/5x7+...+1/97x99=?RT 1x3＋2x4＋3x5＋4x6……＋100x102＝? 1x2+2x3+3x4+4x5+5x6+6x7+7x8+8x9+9x10+10x11 (2X2)/1X3+(4X4)/(3X5)+(6X6)/(5X7)+...+(20X20)/(19X21)==? 1x2+2x3+3x4+4x5+5x6+6x7+7x8+8x9= 1x1-2x2+3x3-4x4+5x5-6x6.-100x100+101x101简便算法答案 2013/1x2+2013/2X3+2013/3X4+2013/4X5+2013/5X6简便计算,