jkhjgq 2010-10-18 20:39
请教1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+...+1/(2005*2006)=
请教1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+...+1/(2005*2006)=.
君彦妈妈 2010-10-18 20:48
1/(2*3)=1/2-1/3
1/(3*4)=1/3-1/4
同理
可以得出,1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+...+1/(2005*2006)= 1-1/2006=2005/2006.