1x2/1+2x3/1+3x4/1+…+2008x2009/1=?

网友回答

1x2分之1+2X3分之1+3X4分之1+.+2007X2008分之1+12008X2009分之1
=1-(1/2)+(1/2)-(1/3)+(1/3)-(1/4)+...+(1/2007)-(1/2008)+(1/2008)-(1/2009)
=1-(1/2009)
=2008/2009
======以下答案可供参考======
供参考答案1:
1x2分之1=1/(1*2)=1-(1/2)
2X3分之1=1/(2*3)=(1/2)-(1/3)
3X4分之1=1/(3*4)=(1/3)-(1/4)
................
供参考答案2:
1x2/1+2x3/1+3x4/1+…+2008x2009/1
=1-1/2+1/2-1/3+1/3-1/4+...+1/2008-1/2009
=1-1/2009
=2008/2009
;