谁般偶求下,感激不尽1/(1*2*3)+1/(2*3*4)+1/(3*4*5)...+1/(100*101*102)注意到1/n*(n+1)*(n+2)=1/2*[1/n*(n+1)-1/(n+1)(n+2)]= 1/2{[1/n-1/(n+1)]-[1/(n+1)-1/(n+2)]}=1/2*[1/n-2/(n+1)+1/(n+2)] 所以原式=1/2[(1-1/101)-(1/2-1/102)]=50/101-2
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