计算:1除以括号1/2+1/6+1/12+1/20+...1/72等于几

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计算:1除以括号1/2+1/6+1/12+1/20+...1/72等于几
计算:1除以括号1/2+1/6+1/12+1/20+...1/72等于几

计算:1除以括号1/2+1/6+1/12+1/20+...1/72等于几
1/2+1/6+1/12+1/20+...1/72
=1-1/2 + 1/2-1/3 + 1/3-1/4 + ...+ 1/8 - 1/9
=1-1/9 = 8/9
∴1/(1/2+1/6+1/12+1/20+...1/72)=9/8