解ï¼1+1/4+9/20+11/30+23/42+15/56+17/72+19/90
=1+1/4+ï¼1/2-1/20ï¼+(1/30+1/3ï¼+(1/2+1/21)ï¼16/56-1/56ï¼+ï¼18/72-1/72ï¼+(18/90+1/90)
=1+1/4+1/2-1/20+1/30+1/3+1/2+1/21+1/4-1/56+1/4-1/72+1/5+1/90
=1+(1/4+1/4)+(1/2+1/2)+(1/5+1/4-1/20)+(1/3+1/21)+(1/30+1/90)+(-1/56-1/72)
=1+3+2/5+2/45+8/21-2/63
=4+(1/21-2/63)+(2/5+2/45)
=4+ 1/63+4/9
=4+29/63
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