1/2 = 1/(1x2) = 1 - 1/2
1/6 = 1/(2x3) = 1/2 - 1/3
1/12 = 1/(3x4) = 1/3 - 1/4 ........ 1/n = 1/(nx(n+1)) = 1/n - 1/(n+1) 1 /2 + 1/6 + 1/12 + 1/20 + 1/30 +...+ 1/n = 1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 +...+1/n - 1/(n+1) = 49/50 Hay A = 1 - 1/(n+1) = 49/50 => 1/(n+1) = 1 - 49/50 1/(n+1) = 1/50 Suy ra n+1=50 nên n=49
A= 1/2 + 1/6 +1/12+1/20+1/30+...+1/n
A=49/50
Tìm n.
Cho A=1/2+1/6+1/12+1/20+1/30+...+1/n. Biết A=49/50 tìm n .
Cho A=1/2+1/6+1/12+1/20+1/30+.....+1/n
Biết A=49/50
Tìm N
Cho A= 1/2 + 1/6 + 1/12 + 1/20 + 1/30 + ....+ 1/n
Biết A = 49/50 tìm n
A=1/2+1/6+1/12+1/20+1/30+...+1/n biet A=49/50
A = 1/2 + 1/6 + 1/12 + 1/20 + 1/30 + 1/n
A = 49/50
Tim n
Cho A = 1/2 + 1/6 + 1/12 + 1/20 +1/30 + ....... + 1/n . Biết A = 49/50 . Tìm n .
| 1560 | 2450 |
A= 1/2 + 1/6 + 1/12 + 1/20 .......+ 1/n
Tìm n biết A là 49/50
CHO A=1/2+1/6+1/12+1/20+1/30+......+1/n
biet A =49/50 TIM n
GIUP MINH NHA CAC BN
