B=1/20+1/30+1/42+1/56+1/72+1/90+1/110

2 câu trả lời

B=120+130+142+156+172+190+1110

=14.5+15.6+16.7+17.8+18.9+19.10+110.11

=14-15+15-16+16-17+17-18+18-19+19-110+110-111

=14-111

=744

 

B=120+130+142+156+172+190+1110

=14.5+15.6+16.7+17.8+8.9+19.10+110.11

=14-15+15-16+16-17+17-19+19-111/10-111

=14-111

=744