1/3+1/6+1/10+1/15+1/21+1/28+1/36+1/45用最简单的方法做出答案.
问题描述：
1/3+1/6+1/10+1/15+1/21+1/28+1/36+1/45用最简单的方法做出答案.
答
1/3(1+1/2)+1/5(1/2+1/3)+1/7(1/3+1/4)+1/9(1/4+1/5)+1/11(1/5+1/6)+1/13(1/6+1/7)+1/15(1/7+1/8) =1/3*3/2+1/5*5/6+1/7*7/12+1/9*9/20+1/11*11*30+1/13*13/42+1/15*15/56 =1/2+1/6+1/12+1/20+1/30+1/42+1/56 =1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8 =1-1/8 =7/8
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