原式=(-1/2)+(+1/3)+(-1/4)+(+1/9)+(+1/8)+(-4/9)
=[(+1/9)+(-4/9)]+(+1/3)+[(-1/2)+(-1/4)]+(+1/8)
=[-(4/9-1/9)]+(+1/3)+[-(1/2+1/4)]+(+1/8)
=[(-1/3)+(+1/3)]+[(-3/4)+(+1/8)]
=0+[-(3/4-1/8)]
=-(6/8-1/8)
=-5/8
(-二分之一)+(+三分之一)+(-四分之一)+(+九分之一)+(+八分之一)+(-九分之四)=
(-二分之一)+(+三分之一)+(-四分之一)+(+九分之一)+(+八分之一)+(-九分之四)=
数学人气:221 ℃时间:2019-10-10 04:55:03
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