1/(1×3)+1/(2×4)+1/(3×5)+……+1/(9×11)=?
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1/(1×3)+1/(2×4)+1/(3×5)+……+1/(9×11)=?1/(1×3)+1/(2×4)+1/(3×5)+……+1/(9×11)=?1/(1×3)+1/(2×4)+1/(3×5)+……
1/(1×3)+1/(2×4)+1/(3×5)+……+1/(9×11)=?
1/(1×3)+1/(2×4)+1/(3×5)+……+1/(9×11)=?
1/(1×3)+1/(2×4)+1/(3×5)+……+1/(9×11)=?
原式=(1-1/3+1/2-1/4+1/3-1/5+……+1/9-1/11)/2 =(1+1/2-1/10-1/11)/2 =(3/2-21/110)/2 =72/110 =36/55
200*(1-1/2)*(1-1/3)*(1-1/4)*.*(1-1/100)
(1-2/1)*(1-3/1)*(1-4/1)*.*(1-2007/1)*(1-2008/1)
(1-1/2)(1-1/3)(1-1/4).(1-1/100)
(-1/2)-(-1/3)-(+1/4)
1.(1+1/2+1/3+1/4)*(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4)=2.(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4+1/5+1/6)-(1+1/2+1/3+1/4+1/5+1/6)*(1/2+1/3+1/4+1/5)=
(-1×1/2)+(-1/2×1/3)+(-1/3×1/4)+…+(-1/2008×1/2009)
(-1*1/2)+(-1/2*1/3)+(-1/3*1/4).(-1/2012*1/2013)
1 2 3 4 ()
-1/2+(-1/6)-(-1/4)-2/3
1/2-(3/4-3/8),1/2+1/4-1/6 ,2/3+(1/2+1/4),1/2-(3/4-3/8),1/2+1/4-1/6 ,2/3+(1/2+1/4),
1/2-(3/4-3/8), 1/2+1/4-1/6 , 2/3+(1/2+1/4),1/2-(3/4-3/8), 1/2+1/4-1/6 , 2/3+(1/2+1/4),
1/2-(3/4-3/8),1/2+1/4-1/6 ,2/3+(1/2+1/4),1/2-(3/4-3/8),1/2+1/4-1/6 ,2/3+(1/2+1/4),
(1*2)/1+(2*3)/1+(3*4)/1+.+2010*2011/1
(1+2/1)(1+4/1)(1+6/1).(1+10/)(1-3/1)(1—5/1).(1-9/1)
(1+1/2+1/3+1/4)×(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)×(1/2+1/3+1/4)~
(1+1/2+1/3+1/4)乘以(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)乘以(1/2+1/3+1/4)简算
(1/2+1/3+1/4+1/6)*24
计算:2(3+1)(3^2+1)(3^4+1).(3^16+1)+1