1-(1\2+1\3+1\5+1\7)+(1\6+1\15+1\21+1\35+1\14)-(1\42+1\105+1\
1个回答

原式=1-(12+13+15+17)+(1/2-1/3+1/6-1/10+1/12-1/28+1/10-1/14+114)-(1/6-1/7+1/56-1/120+170+130)+1210

=1-1/2-1/3-1/5-1/7+1/2-1/3+1/6-1/10+1/3-1/4-1/28+1/10-1/6+1/7-1/7+1/8+1/120-1/70-1/30+1/210

=1-1/3-1/5-1/7-1/4-1/28+1/8+1/120-1/70-1/30+1/210

=1-8/15-12/28+16/120-10/210+1/210

=1-8/15-3/7+2/15-9/210

=1-2/5-3/7-3/70

=1-61/70

=9/70