B=91/2+5/6+11/12+19/20+...+89/90)x100
C=1/2+5/6+11/12+19/20+....+89/90 = ?
1/2+5/6+11/12+19/20+......+89/90
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
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
A=1/2+5/6+11/12+19/20+29/30+41/42+71/72+89/90
Ai có thể giải giúp mình với thi violipic mà chẳng tìm ra kết quả
1+1+2*8+9+10...88+88+89*8+90+91.
1/2+5/6+11/12+19/20+41/42+55/56+71/72+89/90
Tính : 1/2 + 5/6 + 11/12 + 19/20 + ......... + 71/71 + 89/90