1/(2×3)+1/(3×4)+1/(4×5).+1/(9×10)这道题怎么做?三十分钟内有加分.
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1/(2×3)+1/(3×4)+1/(4×5).+1/(9×10)这道题怎么做?三十分钟内有加分.1/(2×3)+1/(3×4)+1/(4×5).+1/(9×10)这道题怎么做?三十分钟内有加分.1/
1/(2×3)+1/(3×4)+1/(4×5).+1/(9×10)这道题怎么做?三十分钟内有加分.
1/(2×3)+1/(3×4)+1/(4×5).+1/(9×10)这道题怎么做?
三十分钟内有加分.
1/(2×3)+1/(3×4)+1/(4×5).+1/(9×10)这道题怎么做?三十分钟内有加分.
=1/3(1/2+1/4)+1/5(1/4+1/6)+1/7(1/6+1/8)+1/8*9
=1/4+1/12+1/24+1/72
=7/18
上面那位大哥,7/45 是错的哦,你想想小学也不过为教他们积化和差.不至于用到归纳法
我够笨的了,我查了下小学教材确实有归纳法了,现在的小朋友太苦了.
各个项可化为1/(n+1)(n+2) n=1,2,3.8
1/(n+1)(n+2)=1/(n+1)-1/(n+2)
你把n=1,2,3...8的每一项都带进去
原式=1/2-1/9=7/18
上面那位仁兄公式是对的不过结果给错了,小朋友千万别做错了.
数学平时多做下题,一切就OK了.
1 2 3 4 ()
1()2()3()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-(3/4-3/8),1/2+1/4-1/6 ,2/3+(1/2+1/4),
(-1/2)-(-1/3)-(+1/4)
-1/2+(-1/6)-(-1/4)-2/3
200*(1-1/2)*(1-1/3)*(1-1/4)*.*(1-1/100)
计算((1/3)^2)×4^0+((1/3)^4)×4^1+((1/3)^6)×4^2+…+((1/3)^2n)×4^(n-1)
1/4-(1/2-1/3)-4(3/4-1)
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)=
(1,1,1).(2,4,8)...3Q
(1-2/1)*(1-3/1)*(1-4/1)*.*(1-2007/1)*(1-2008/1)
(1*2)/1+(2*3)/1+(3*4)/1+.+2010*2011/1
(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4(3^2+1)(3^4+1).(3^2006+1)