1/（1x3）+1/（2x4）+1/（3x5）+1/(4x6)+1/(5x7)+1/(6x8)的答案
问题描述：
1/（1x3）+1/（2x4）+1/（3x5）+1/(4x6)+1/(5x7)+1/(6x8)的答案
答
1/(1x3)+1/(2x4)+1/(3x5)+1/(4x6)+1/(5x7)+1/(6x8)=[1/(1*3)+1/(2*4)+1/(3*5)+1/(4*6)+1/(5*7)+1/(6*8)]*[2*(1/2)]=[2/(1*3)+2/(2*4)+2/(3*5)+2/(4*6)+2/(5*7)+2/(6*8)]*(1/2)=[(1-1/3)+(1/2-1/4)+(1/3-1/5)+(1/4-1/...