4分之一加28分之1加70分之1加130分之1加 - 知识问答

4分之一加28分之1加70分之1加130分之1加208分之1怎么做？过程，简便计算，谢谢，立刻

1个回答

1/4+1/28+1/70+1/130+1/208
=1/4+1/3×(1/4-1/7)+1/3×(1/7-1/10)+1/3×(1/10-1/13)+1/3×(1/13-1/16)
=1/4+1/3×(1/4-1/7+1/7-1/10+1/10-1/13+1/13-1/16)
=1/4+1/3×(1/4-1/16)
=1/4+1/3×1/4-1/3×1/16
=1/4×(1+1/3)-1/48
=1/3-1/48
=15/48
=5/16

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