1/2+1/4+1/6+1/8+1/10+1/12+1/14+1/16+1/18+1/20=(1/2+1/8)+(1/4+1/6)+(1/10+1/20)+(2/12+1/18)+(1/14+1/16)
=5/8+5/12+3/20+2/9+15/112
=25/24+67/180+15/112
=509/360+15/112
=143/120
Tính nhanh:
a,1/4+2/5+6/8+9/15+8/1
b,1/2+2/4+3/6+4/8+5/10+6/12+7/14+8/16+9/18+10/20
c,1/10+4/20+9/30+16/40+25/50+36/60+49/70+64/80+81/90
Tính nhanh:
a,1/4+2/5+6/8+9/15+8/1
b,1/2+2/4+3/6+4/8+5/10+6/12+7/14+8/16+9/18+10/20
c,1/10+4/20+9/30+16/40+25/50+36/60+49/70+64/80+81/90
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18 + 20
1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19
tính nhanh
1+1+2+2+3+3+4+4+5+5+6+6+7+7+8+9+8+9+10+12+13+14+15+16+17+18+19+20+30+1000000=?
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20=?
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20
1+2+3-4+5+6-7+8+9-10+11+12-13+14+15-16+17+18-19+20:15x2
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+.........................50= ?
a) 1+3+5+7+.....+99
b)1+4+7+...28
c) 24-22+20-18+16-14+12-10+8-6
giúp mh với mh đang cần gấp huhu
